Crystalline sulfide solid electrolyte

Abstract

Provided is a crystalline sulfide solid electrolyte that has high ion conductivity, achieves a low raw material cost, and includes a lithium atom, a phosphorus atom, a sulfur atom, an oxygen atom, and a halogen atom. In an X-ray diffraction measurement using a CuKα ray, diffraction peaks of the crystalline sulfide solid electrolyte exist at 2θ=20.3±0.5° and 29.6±0.6°. A peak derived from PSO3 3- is observed at 39.6±5.0 ppm in solid 31P-NMR measurement. The crystalline sulfide solid electrolyte has a composition represented by composition formula (100-y)(0.5)(Li3+2zP(S1-xOx)4+z)+(y)LiX (in the composition formula, x, y, and z satisfy 0.00060≤x≤0.15, 3.0≤y<25.0, and -0.17≤z≤1.5, respectively, and X represents a halogen atom).

Description

Crystalline sulfide solid electrolyte

[0001] The present invention relates to a crystalline sulfide solid electrolyte.

[0002] In recent years, the rapid spread of information-related devices and communication devices such as personal computers, video cameras, and mobile phones has placed great importance on the development of batteries for use as their power sources. Lithium-ion batteries, in particular, have attracted attention due to their high energy density. Traditionally, batteries used for such applications have used electrolytes containing flammable organic solvents, necessitating the installation of safety devices to suppress temperature rise during short circuits, as well as improvements in the structure and materials to prevent short circuits. In response to this issue, development is underway to develop batteries that use solid electrolytes, eliminating the need for flammable organic solvents, simplifying safety devices, and improving manufacturing costs and productivity.

[0003] Various types of solid electrolytes have been developed for use in the solid electrolyte layer. For example, Patent Document 1 discloses a solid electrolyte containing lithium (Li), phosphorus (P), sulfur (S), oxygen (O), and a halogen element, with a sulfur / oxygen molar ratio of 0.2 to 100. Patent Document 2 discloses L ａ M ｂ P ｃ S ｄ X ｅ O ｆ A solid electrolyte glass represented by (1') (L represents an alkali metal, M represents one or more halogen elements selected from B, Al, Si, Ge, etc., and X represents one or more halogen elements selected from I, Cl, Br, and F, and X includes at least Br) and a method for producing the same are disclosed. Patent Document 3 also discloses a sulfide solid electrolyte material having an ionic conductor having an ortho composition and LiI, wherein the ionic conductor contains oxygen.

[0004] JP 2014-93263 A JP 2014-93261 A JP 2014-89986 A

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a sulfide solid electrolyte that has high ionic conductivity and also realizes a reduction in raw material costs.

[0006] The crystalline sulfide solid electrolyte according to the present invention contains lithium atoms, phosphorus atoms, sulfur atoms, oxygen atoms, and halogen atoms, and has diffraction peaks at 2θ=20.3±0.5° and 29.6±0.6° in X-ray diffraction measurement using CuKα rays, and ３１ P-NMR measurement revealed that PSO was 39.6±5.0 ppm. ３ ３－ A crystalline sulfide solid electrolyte in which a peak due to (Li) is observed and which has a composition represented by the following composition formula (1): ３＋２ｚ P (S １－ｘ O ｘ ) ４＋ｚ )+(y)LiX (1) (In composition formula (1), x, y, and z each satisfy 0.00060≦x≦0.15, 3.0≦y<25.0, and −0.17≦z≦1.5. X represents a halogen atom.)

[0007] The crystalline sulfide solid electrolyte according to the present invention contains lithium atoms, phosphorus atoms, sulfur atoms, oxygen atoms, and halogen atoms, and has diffraction peaks at 2θ=20.3±0.5° and 29.6±0.6° in X-ray diffraction measurement using CuKα rays, and is a solid ３１ P-NMR measurement revealed that PSO was 39.6±5.0 ppm. ３ ３－ The peaks due to the crystalline sulfide solid electrolyte are observed.

[0008] According to the present invention, it is possible to provide a sulfide solid electrolyte that has high ionic conductivity and also realizes a reduction in raw material costs.

[0009] 1 is an X-ray diffraction pattern of a crystalline sulfide solid electrolyte obtained in an example. 2 is an X-ray diffraction pattern of a crystalline sulfide solid electrolyte obtained in an example. 3 is an X-ray diffraction pattern of a crystalline sulfide solid electrolyte obtained in an example. 4 is an X-ray diffraction pattern of a crystalline sulfide solid electrolyte obtained in an example. 5 is an X-ray diffraction pattern of a crystalline sulfide solid electrolyte obtained in an example. 6 is an X-ray diffraction pattern of a crystalline sulfide solid electrolyte obtained in an example. 7 is an X-ray diffraction pattern of a crystalline sulfide solid electrolyte obtained in a comparative example. 8 is an X-ray diffraction pattern of a crystalline sulfide solid electrolyte obtained in a comparative example. ３１ 1 is a P-NMR spectrum of the crystalline sulfide solid electrolyte obtained in the example. ３１ P-NMR spectrum.

[0010] Hereinafter, an embodiment of the present invention (hereinafter, sometimes referred to as "the present embodiment") will be described. In this specification, the upper and lower limit values ​​of a range expressed by "greater than or equal to," "less than or equal to," and "to" can be arbitrarily combined, and the numerical values ​​in the examples can also be used as the upper and lower limit values.

[0011] (Findings Obtained by the Inventors to Achieve the Present Invention) As a result of intensive research aimed at solving the above-mentioned problems, the inventors have discovered the following and have completed the present invention. As disclosed in Patent Documents 1 to 3, the development of solid electrolytes has so far focused primarily on improving the performance of solid electrolytes, such as ionic conductivity and hydrolysis resistance. However, in recent developments aimed at the practical application of all-solid-state batteries, attention has been focused not only on improving these various performances but also on reducing raw material costs.

[0012] The solid electrolyte disclosed in Patent Document 1 contains lithium (Li), phosphorus (P), sulfur (S), oxygen (O), and a halogen. The inclusion of oxygen improves hydrolysis resistance, i.e., suppresses the generation of hydrogen sulfide, while the inclusion of halogen improves ionic conductivity. However, the ionic conductivity is 0.21 to 2.2 mS / cm, which is not high considering the amount of halogen-containing raw material used. Because halogen-containing raw materials are expensive among solid electrolyte raw materials, the solid electrolyte disclosed in Patent Document 1 leaves room for improvement in terms of reducing raw material costs. Furthermore, the ionic conductivity is not high considering the amount of halogen used, leaving room for improvement in terms of improving ionic conductivity. Furthermore, the solid electrolyte disclosed in Patent Document 1 does not have the diffraction peaks of the crystalline sulfide solid electrolyte of this embodiment.

[0013] The solid electrolyte glass disclosed in Patent Document 2 is a solid electrolyte glass represented by the above composition formula (1') containing alkali metals such as lithium, phosphorus, sulfur, halogens, and oxygen, as well as metal elements such as B, Al, and Si. Patent Document 2 also describes a glass ceramic obtained by heat-treating the solid electrolyte glass, but the ionic conductivity is 0.80 to 2.2 mS / cm, which is not high considering the amount of raw material used, including halogens. Therefore, like the solid electrolyte disclosed in Patent Document 1, there is room for improvement in terms of reducing raw material costs and improving ionic conductivity. Furthermore, the solid electrolyte disclosed in Patent Document 2 does not have the diffraction peaks of the crystalline sulfide solid electrolyte of the present embodiment.

[0014] The sulfide solid electrolyte material disclosed in Patent Document 3 contains LiI and oxygen. While the inclusion of LiI improves ionic conductivity while decreasing chemical stability, the oxygen suppresses the decrease in chemical stability. Paragraph

[0010] of Patent Document 3 states that the material is highly amorphous to the extent that it has a glass transition point, thereby increasing Li ion conductivity. Furthermore, the examples disclose an amorphous material that exhibits a halo pattern in X-ray diffraction (XRD) measurements, which is different from crystalline sulfide solid electrolytes. Furthermore, according to the examples in Patent Document 3, the ionic conductivity is 0.6 to 1.2 mS / cm, which is not high considering the amount of raw material containing a halogen element used. Therefore, like the solid electrolyte disclosed in Patent Document 1, there is room for improvement in terms of reducing raw material costs and improving ionic conductivity.

[0015] Thus, Patent Documents 1 to 3 focus on improving ionic conductivity and hydrolysis resistance, but none of them can be said to have high ionic conductivity considering the amount of raw materials containing halogen elements used. Furthermore, Patent Documents 1 to 3 attempt to improve ionic conductivity by using halogen elements, but such a technique is known as common technical knowledge, even without mentioning these patent documents. Taking these factors into consideration, Patent Documents 1 to 3 do not provide any motivation to reduce the amount of halogen elements used in order to improve ionic conductivity. Furthermore, these patent documents do not disclose any idea of ​​achieving high ionic conductivity and further reducing raw material costs by adding oxygen atoms to a sulfide solid electrolyte. Thus, it cannot be said that conventional techniques such as Patent Documents 1 to 3 have produced sulfide solid electrolytes that have high ionic conductivity and also reduce raw material costs.

[0016] Until now, it has been thought that only a few compositions can be used to obtain crystal structures that exhibit high ionic conductivity, such as the thiolicon region II crystal structure and the LGPS crystal structure obtained in the examples described below. Furthermore, as will be shown in the comparative examples described below, simply reducing the amount of halogen atoms used without including oxygen atoms does not result in the development of these crystal structures, and the ionic conductivity also decreases.

[0017] The present inventors focused on replacing some of the sulfur atoms in a sulfide solid electrolyte with oxygen atoms, and as a result of further development, discovered that a sulfide solid electrolyte containing lithium atoms, phosphorus atoms, sulfur atoms, oxygen atoms, and halogen atoms and having a predetermined diffraction peak has high ionic conductivity and also reduces raw material costs, more specifically, has high ionic conductivity while reducing raw material costs, and can further improve ionic conductivity when using a large amount of expensive raw materials such as lithium halide.

[0018] The above Patent Documents 1 to 3 do not pay any attention to the fact that high ionic conductivity can be achieved and raw material costs can be reduced by replacing some sulfur atoms with oxygen atoms and by providing a material with a predetermined diffraction peak, and in particular, they do not pay any attention to the idea of ​​reducing raw material costs by incorporating oxygen atoms as a substitute for sulfur atoms. Thus, the fact that high ionic conductivity can be achieved while reducing raw material costs by containing lithium atoms, phosphorus atoms, sulfur atoms, oxygen atoms, and halogen atoms and providing a material with a predetermined diffraction peak is a surprising phenomenon that has not been recognized until now.

[0019] In this specification, the term "solid electrolyte" refers to an electrolyte that maintains a solid state under a nitrogen atmosphere at 25° C. The "sulfide solid electrolyte" of this embodiment is a solid electrolyte that contains oxygen atoms in addition to lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, and has ionic conductivity due to the lithium atoms.

[0020] The term "sulfide solid electrolyte" includes both crystalline sulfide solid electrolytes having a crystalline structure and amorphous sulfide solid electrolytes. In this specification, a crystalline sulfide solid electrolyte is a solid electrolyte in which a peak derived from the solid electrolyte is observed in the X-ray diffraction pattern in powder X-ray diffraction (XRD) measurement, regardless of whether or not a peak derived from the raw material of the solid electrolyte is present. That is, a crystalline sulfide solid electrolyte includes a crystalline structure derived from the solid electrolyte, and a portion of the crystalline structure may be derived from the solid electrolyte, or the entire crystalline structure may be derived from the solid electrolyte. Furthermore, as long as the crystalline sulfide solid electrolyte has the X-ray diffraction pattern described above, it may also include an amorphous sulfide solid electrolyte (also referred to as a "glass component") as a portion of the crystalline sulfide solid electrolyte. Therefore, the crystalline sulfide solid electrolyte includes so-called glass ceramics obtained by heating an amorphous solid electrolyte (glass component) above its crystallization temperature.

[0021] In this specification, the amorphous sulfide solid electrolyte (glass component) refers to a solid electrolyte in which the X-ray diffraction pattern in powder X-ray diffraction (XRD) measurement is a halo pattern in which no peaks other than those derived from the material are observed, and it does not matter whether or not there are peaks derived from the raw materials of the solid electrolyte.

[0022] (Regarding various aspects of the present embodiment) A sulfide solid electrolyte according to a first aspect of the present embodiment contains lithium atoms, phosphorus atoms, sulfur atoms, oxygen atoms, and halogen atoms, and has diffraction peaks at 2θ=20.3±0.5° and 29.6±0.6° in X-ray diffraction measurement using CuKα rays, and is a solid ３１ P-NMR measurement revealed that PSO was 39.6±5.0 ppm. ３ ３－ A crystalline sulfide solid electrolyte in which a peak due to (Li) is observed and which has a composition represented by the following composition formula (1): ３＋２ｚ P (S １－ｘ O ｘ ) ４＋ｚ)+(y)LiX (1) (In composition formula (1), x, y, and z each satisfy 0.00060≦x≦0.15, 3.0≦y<25.0, and −0.17≦z≦1.5. X represents a halogen atom.)

[0023] As described above, the crystalline sulfide solid electrolyte of this embodiment contains lithium atoms, phosphorus atoms, sulfur atoms, oxygen atoms, and halogen atoms, has the above-mentioned predetermined diffraction peak, and has a composition represented by the above-mentioned predetermined composition formula, thereby having high ionic conductivity and enabling reduction in raw material costs. Regarding high ionic conductivity, it is known that the use of lithium halide can improve ionic conductivity, as described above. On the other hand, lithium halide is expensive, and reducing its usage leads to reduced raw material costs, but usually also leads to a decrease in ionic conductivity. In other words, reduced raw material costs and high ionic conductivity are in a trade-off relationship.

[0024] The crystalline sulfide solid electrolyte of this embodiment has a predetermined diffraction peak and a solid state diffraction peak in X-ray diffraction measurement while substituting some of the sulfur atoms with oxygen atoms. ３１By having a predetermined peak in P-NMR measurement and a composition represented by the above-mentioned predetermined composition formula, raw material costs can be reduced, that is, high ionic conductivity can be achieved even when the amount of raw material containing halogen atoms, such as lithium halide, used is reduced. Furthermore, when a large amount of raw material containing halogen atoms, such as lithium halide, is used, even if the amount used is similar to that in the prior art such as Patent Documents 1 to 3, a higher ionic conductivity can be achieved (hereinafter, when simply referred to in this specification as "high ionic conductivity," it means either a high ionic conductivity obtained even when the amount of raw material containing halogen atoms is reduced, a higher ionic conductivity obtained when the amount used is large, or both). Thus, the crystalline sulfide solid electrolyte of this embodiment can achieve high ionic conductivity and also reduce raw material costs. Furthermore, when a large amount of raw material containing halogen atoms is used (including cases where it is similar to or greater than Patent Documents 1 to 3), it cannot be said that raw material costs are reduced, but it becomes an extremely useful solid electrolyte in that it can obtain a higher ionic conductivity than conventionally obtained.

[0025] The crystalline sulfide solid electrolyte according to a second aspect of the present embodiment is the crystalline sulfide solid electrolyte of the first aspect, wherein in the composition formula (1), the product of x and y (x × y) is 0.0010 or more and 2.7 or less.

[0026] In composition formula (1), x and y can each be any value selected from the above range. However, when the product of x and y is a value within the above range, the value is well-balanced, making it easier to obtain a crystalline sulfide solid electrolyte with high ionic conductivity while reducing raw material costs. More specifically, this is considered as follows. As described below, x represents the substitution rate of oxygen atoms when some sulfur atoms are replaced with oxygen atoms, and y represents the content of halogen atoms. Therefore, when the product of these is within the above range, it means that the amount of oxygen atoms and the amount of halogen atoms can be balanced. By replacing sulfur atoms with oxygen atoms, the crystal lattice size can be reduced, and by further balancing the amount of oxygen atoms and the amount of halogen atoms, crystal structures with high ionic conductivity, such as a thiolicon region II crystal structure and an LGPS crystal structure, can be stabilized. Therefore, it is thought that the content of halogen atoms, which has been considered necessary for stabilizing these crystal structures capable of exhibiting high ionic conductivity, can be reduced, which means that it is easier to simultaneously achieve reduced raw material costs and high ionic conductivity.

[0027] The crystalline sulfide solid electrolyte according to a third aspect of the present embodiment is the crystalline sulfide solid electrolyte according to the first or second aspect, wherein ３１ P-NMR measurement revealed that PO was present at 9.2±5.0 ppm. ４ ３－ A crystalline sulfide solid electrolyte according to a fourth aspect is any one of the first to third aspects, wherein a peak due to ３１ P-NMR measurement revealed that PS was present at 70.3±5.0 ppm. ２ O ２ ３－ A peak due to this is observed.

[0028] solid ３１ When the above peaks are observed by P-NMR measurement, the crystalline sulfide solid electrolyte of this embodiment is likely to exhibit peaks at 2θ = 20.3 ± 0.5° and 29.6 ± 0.6°. As a result, a crystalline sulfide solid electrolyte having high ionic conductivity can be easily obtained while reducing raw material costs.

[0029] The crystalline sulfide solid electrolyte according to a fifth aspect of the present embodiment is any one of the first to fourth aspects, wherein at least two exothermic peaks are measured in thermogravimetric differential calorimetry (measured at a heating rate of 10°C / min), and the temperature difference between the peak tops of the two exothermic peaks is 20°C or more and 110°C or less.

[0030] When the two exothermic peaks are observed in thermogravimetric differential calorimetry, the crystalline sulfide solid electrolyte of this embodiment is likely to exhibit diffraction peaks at 2θ = 20.3 ± 0.5° and 29.6 ± 0.6°. As a result, a crystalline sulfide solid electrolyte having high ionic conductivity can be easily obtained while reducing raw material costs.

[0031] A crystalline sulfide solid electrolyte according to a sixth aspect of the present embodiment is the crystalline sulfide solid electrolyte of any one of the first to fifth aspects described above, wherein the halogen atom is at least one halogen atom selected from a chlorine atom, a bromine atom, and an iodine atom. A crystalline sulfide solid electrolyte according to a seventh aspect is the crystalline sulfide solid electrolyte of any one of the first to sixth aspects described above, wherein the halogen atom is a bromine atom and an iodine atom.

[0032] Higher ionic conductivity can be easily obtained by using at least one halogen atom selected from chlorine, bromine, and iodine atoms as the halogen atom, i.e., chlorine, bromine, or iodine atoms alone or two or more halogen atoms selected from these atoms. In particular, the simultaneous use of bromine and iodine atoms can easily obtain particularly high ionic conductivity.

[0033] The crystalline sulfide solid electrolyte according to an eighth aspect of the present embodiment is any one of the first to seventh aspects, wherein in the composition formula (1), y satisfies 14.0<y<25.0.

[0034] The crystalline sulfide solid electrolyte of this embodiment has a specific composition represented by the composition formula (1), which makes it easy to exhibit diffraction peaks at 2θ = 20.3 ± 0.5° and 29.6 ± 0.6°. This makes it easier to obtain a crystalline sulfide solid electrolyte with high ionic conductivity while reducing raw material costs. In the composition formula (1), when y is 14.0 < y < 25.0, this means that a larger amount of raw material containing halogen atoms is used, i.e., the crystalline sulfide solid electrolyte has a higher halogen atom content, which is also considered for sulfide solid electrolytes in the prior art. However, the crystalline sulfide solid electrolyte of this embodiment makes it easy to exhibit diffraction peaks at 2θ = 20.3 ± 0.5° and 29.6 ± 0.6°, and thus exhibits a higher ionic conductivity than that of sulfide solid electrolytes in the prior art.

[0035] The crystalline sulfide solid electrolyte according to a ninth aspect of the present embodiment is any one of the first to eighth aspects described above, wherein the ionic conductivity is 0.85 mS / cm or more, and the crystalline sulfide solid electrolyte according to a tenth aspect is any one of the first to ninth aspects described above, wherein the ionic conductivity is 2.5 mS / cm or more.

[0036] The crystalline sulfide solid electrolyte of this embodiment contains lithium atoms, phosphorus atoms, sulfur atoms, oxygen atoms, and halogen atoms and has a predetermined diffraction peak, so that the ionic conductivity is high as in the above range. It has ionic conductivity.

[0037] A crystalline sulfide solid electrolyte according to an eleventh aspect of the present embodiment is any one of the first to tenth aspects, wherein the crystalline sulfide solid electrolyte does not contain at least one metal atom selected from sodium atoms, boron atoms, aluminum atoms, silicon atoms, germanium atoms, arsenic atoms, selenium atoms, antimony atoms, tellurium atoms, lead atoms, and bismuth atoms.

[0038] The crystalline sulfide solid electrolyte of this embodiment does not contain the above metal atoms, which makes it easier to exhibit diffraction peaks at 2θ = 20.3 ± 0.5° and 29.6 ± 0.6° and reduces the impurity content. As a result, a crystalline sulfide solid electrolyte having high ionic conductivity can be easily obtained while reducing raw material costs.

[0039] A crystalline sulfide solid electrolyte according to a twelfth aspect of the present embodiment is any one of the first to eleventh aspects, wherein the oxygen atoms are P ２ O ５ The theory is that it originates from

[0040] When producing the crystalline sulfide solid electrolyte of this embodiment, P ２ O ５ By adopting this, some of the sulfur atoms can be easily replaced with oxygen atoms, and therefore the oxygen atoms can be easily incorporated into the structure of the solid electrolyte. As a result, the crystalline sulfide solid electrolyte of this embodiment is likely to exhibit diffraction peaks at 2θ = 20.3 ± 0.5° and 29.6 ± 0.6°, and as a result, a crystalline sulfide solid electrolyte having high ionic conductivity can be easily obtained while reducing raw material costs.

[0041] The crystalline sulfide solid electrolyte according to a thirteenth aspect of the present embodiment is any one of the first to twelfth aspects, wherein the crystalline sulfide solid electrolyte is a glass ceramic.

[0042] As described above, glass ceramics are obtained by heating an amorphous solid electrolyte (glass component) to a temperature equal to or higher than the crystallization temperature. The crystalline sulfide solid electrolyte obtained in this manner is likely to exhibit diffraction peaks at 2θ=20.3±0.5° and 29.6±0.6°. As a result, a crystalline sulfide solid electrolyte having high ionic conductivity can be easily obtained while reducing raw material costs.

[0043] Further, a crystalline sulfide solid electrolyte according to a fourteenth aspect of the present embodiment includes lithium atoms, phosphorus atoms, sulfur atoms, oxygen atoms, and halogen atoms, and has diffraction peaks at 2θ=20.3±0.5° and 29.6±0.6° in X-ray diffraction measurement using CuKα rays, and ３１ P-NMR measurement revealed that PSO was 39.6±5.0 ppm. ３ ３－ The peaks due to the crystalline sulfide solid electrolyte are observed.

[0044] In the crystalline sulfide solid electrolyte of the present embodiment, specific atoms of the lithium atom, phosphorus atom, sulfur atom, oxygen atom, and halogen atom exhibit predetermined diffraction peaks and solid state diffraction peaks in X-ray diffraction measurement. ３１ By having a structure that exhibits a predetermined peak in P-NMR measurement, raw material costs can be reduced, that is, even when the amount of raw material containing halogen atoms, such as lithium halide, used is reduced, the solid electrolyte has high ionic conductivity. Furthermore, when a large amount of raw material containing halogen atoms is used (including cases where the amount is the same as or greater than that of Patent Documents 1 to 3 above), it cannot be said that raw material costs are reduced, but the solid electrolyte is extremely useful in that it can achieve a higher ionic conductivity than previously achieved. Thus, the crystalline sulfide solid electrolyte of this embodiment is an extremely useful solid electrolyte regardless of the amount of raw material containing halogen atoms.

[0045] A crystalline sulfide solid electrolyte according to a fifteenth aspect of the present embodiment is the crystalline sulfide solid electrolyte of the fourteenth aspect, wherein ３１ P-NMR measurement revealed that PO was present at 9.2±5.0 ppm. ４ ３－ A crystalline sulfide solid electrolyte according to a sixteenth aspect is the crystalline sulfide solid electrolyte according to the fourteenth or fifteenth aspect, wherein a peak due to ３１ P-NMR measurement revealed that PS was present at 70.3±5.0 ppm. ２ O ２ ３－ A peak due to this is observed.

[0046] solid ３１When the above peaks are observed by P-NMR measurement, the crystalline sulfide solid electrolyte according to the fourteenth embodiment is likely to exhibit peaks at 2θ=20.3±0.5° and 29.6±0.6°. As a result, a crystalline sulfide solid electrolyte having high ionic conductivity can be easily obtained while reducing raw material costs.

[0047] [Crystalline sulfide solid electrolyte] The crystalline sulfide solid electrolyte of this embodiment contains lithium atoms, phosphorus atoms, sulfur atoms, oxygen atoms, and halogen atoms, and has diffraction peaks at 2θ=20.3±0.5° and 29.6±0.6° in X-ray diffraction measurement using CuKα rays, and has a composition represented by the following composition formula (1): (100-y)(0.5)(Li ３＋２ｚ P (S １－ｘ O ｘ ) ４＋ｚ )+(y)LiX (1) (In composition formula (1), x, y, and z each satisfy 0.00060≦x≦0.15, 3.0≦y<25.0, and −0.17≦z≦1.5. X represents a halogen atom.)

[0048] (Diffraction Peaks) The crystalline sulfide solid electrolyte of this embodiment has diffraction peaks at 2θ = 20.3 ± 0.5 ° and 29.6 ± 0.6 ° in X-ray diffraction measurement using CuKα radiation, and is therefore a "crystalline" sulfide solid electrolyte. The peak positions of the diffraction peaks possessed by the crystalline sulfide solid electrolyte of this embodiment vary depending on the peak position, but may vary within a range of ± 0.6 ° or ± 0.5 °. The measurement method for X-ray diffraction measurement using CuKα radiation in this specification will be described in the Examples.

[0049] Preferred examples of crystal structures that exhibit diffraction peaks at 2θ = 20.3 ± 0.5 ° and 29.6 ± 0.6 ° include the thiolisicon region II crystal structure, the LGPS crystal structure, etc. The intensities of the diffraction peaks that appear at 2θ = 20.3 ± 0.5 ° and 29.6 ± 0.6 ° differ between the thiolisicon region II crystal structure and the LGPS crystal structure, with the peak intensity of the diffraction peak at 2θ = 20.3 ± 0.5 ° being stronger than the peak intensity of the diffraction peak at 2θ = 29.6 ± 0.6 ° in the thiolisicon region II crystal structure, and the peak intensity of the diffraction peak at 2θ = 29.6 ± 0.6 ° being stronger than the peak intensity of the diffraction peak at 2θ = 20.3 ± 0.5 ° in the LGPS crystal structure.

[0050] The crystalline sulfide solid electrolyte of this embodiment preferably has at least one of a thiolisiconregion II crystal structure and an LGPS crystal structure. This is because diffraction peaks are likely to appear at 2θ = 20.3 ± 0.5 ° and 29.6 ± 0.6 °, and high ionic conductivity is also exhibited. As shown in the examples described later, the crystalline sulfide solid electrolyte of this embodiment includes those having mainly a thiolisiconregion II crystal structure, those having mainly a LGPS crystal structure, and those having a mixture of these crystal structures. The crystalline sulfide solid electrolyte of this embodiment may have any of the above crystal structures as long as it has the above diffraction peaks. Since such diffraction peaks are exhibited, high ionic conductivity can be obtained even when the amount of raw material containing halogen atoms is small (i.e., the content of halogen atoms in the crystalline sulfide solid electrolyte is at least), and when the amount of raw material containing halogen atoms is large (i.e., when the content of halogen atoms in the crystalline sulfide solid electrolyte is large), the crystalline sulfide solid electrolyte has ionic conductivity that is at least as high as that of conventional sulfide solid electrolytes containing halogen atoms to the same extent.

[0051] Here, with regard to "mainly," "mainly having a thiolicon region II crystal structure" means that all of the above diffraction peaks attributable to the thiolicon region II crystal structure can be confirmed, "mainly having an LGPS crystal structure" means that all of the above diffraction peaks attributable to the LGPS crystal structure can be confirmed, and "mixed" means that both diffraction peaks can be confirmed, or that some of the both diffraction peaks overlap and cannot be separated. As a criterion for determining "mainly," for example, if the ratio of a certain crystal structure to the total crystal structure is 60% or more, it can be said that the certain crystal structure is mainly present, and if it is in between, i.e., more than 40% but less than 60%, it can be considered to be mixed.

[0052] Furthermore, when the thiolicon region II crystal structure and the LGPS crystal structure coexist, the term "mainly" can also be determined by the intensity of a predetermined diffraction peak. The intensity of the diffraction peak at 2θ=20.3±0.5° (hereinafter referred to as "I") due to the thiolicon region II crystal structure is １ ") and the intensity of the diffraction peak at 2θ=29.6±0.6° due to the LGPS-type crystal structure (hereinafter referred to as "I ２ ") and I １ >I ２ If so, it is determined that the crystal structure is mainly thiolicon region II type. １ <I ２ If so, it can be determined that the crystal structure is mainly LGPS type. １ ≒I ２ If this is the case (here, "≒" means ±20% or less), it can be determined that the thiolicon region II type crystal structure and the LGPS type crystal structure are mixed.

[0053] The thiolicon region II crystal structure is, for example, Li ４－ｘ Ge １－ｘ P ｘ S ４Thio-LISICON Region II crystal structure (Kanno et al., Journal of the Electrochemical Society, 148(7)A742-746(2001)), Li ４－ｘ Ge １－ｘ P ｘ S ４ Examples of the LGPS type crystal structure include those having a crystal structure similar to the thio-LISICON Region II type (see Solid State Ionics, 177 (2006), 2721-2725). ３＋ｘ P.S. ４－ｙ O ｙ (x satisfies −1≦x≦1, and y satisfies 0<y<4) (also referred to as “Li—P—S—O-based sulfide solid electrolyte”).

[0054] Here, the above "Li ４－ｘ Ge １－ｘ P ｘ S ４ The notation of the crystal structure "thio-LISICON Region II type" means that the crystal structure was found in the above document to be composed of Li, Ge, P, and S atoms. The sulfide solid electrolyte obtained by the production method of this embodiment contains lithium atoms, phosphorus atoms, sulfur atoms, and halogen atoms, and therefore, is not a "Li ４－ｘ Ge １－ｘ P ｘ S ４ "Li in thio-LISICON Region II type" ４－ｘ Ge １－ｘ P ｘ S ４However, when the sulfide solid electrolyte obtained by the manufacturing method of this embodiment has the same diffraction peak as the "thiolisiconregion II type crystal structure" (including the above-mentioned "similar crystal structure"), it can be said that the sulfide solid electrolyte obtained by the manufacturing method of this embodiment has a thiolisiconregion II type crystal structure formed by lithium atoms, phosphorus atoms, sulfur atoms, and halogen atoms. This is not limited to the thiolisiconregion II type crystal structure, but is also true for the LGPS type crystal structure.

[0055] The crystalline sulfide solid electrolyte of this embodiment preferably has at least one peak at 2θ = 23.8° and 37.8° as a peak other than the above diffraction peaks, and more preferably has at least one peak at 2θ = 12.4°, 14.4°, and 31.5°. By further improving the crystallinity, these peaks are expressed, resulting in higher ionic conductivity. As mentioned above, the positions of these diffraction peaks fluctuate within the ranges of ±0.7°, ±0.6°, and ±0.5°.

[0056] The thiolicon region II crystal structure and LGPS crystal structure preferably possessed by the crystalline sulfide solid electrolyte of this embodiment can be formed without using an amorphous solid electrolyte (glass component), or can be formed as a so-called glass ceramic obtained by heating an amorphous solid electrolyte (glass component) to a crystallization temperature or higher. From the viewpoint of further improving crystallinity and consequently obtaining higher ionic conductivity, the crystalline sulfide solid electrolyte of this embodiment is preferably a glass ceramic.

[0057] (Constituent atoms) The crystalline sulfide solid electrolyte of this embodiment contains lithium atoms, phosphorus atoms, sulfur atoms, oxygen atoms, and halogen atoms. Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms. Among these halogen atoms, chlorine atoms, bromine atoms, and iodine atoms are preferred, and bromine atoms and iodine atoms are more preferred. The halogen atoms may contain these atoms alone or multiple types of atoms.

[0058] The oxygen atoms in the crystalline sulfide solid electrolyte of this embodiment are P２ O ５ The method for producing the crystalline sulfide solid electrolyte of this embodiment is not particularly limited as long as it contains lithium atoms, phosphorus atoms, sulfur atoms, oxygen atoms, and halogen atoms and has the above-mentioned diffraction peak. There are also no particular limitations on the raw materials used, but in consideration of the ease of replacing some of the sulfur atoms in the structure of the crystalline sulfide solid electrolyte with oxygen atoms, P is preferably used as a raw material containing oxygen atoms. ２ O ５ It is preferred to use

[0059] Furthermore, the crystalline sulfide solid electrolyte of this embodiment preferably does not contain at least one metal atom selected from sodium atoms, boron atoms, aluminum atoms, silicon atoms, germanium atoms, arsenic atoms, selenium atoms, antimony atoms, tellurium atoms, lead atoms, and bismuth atoms. By not containing these atoms, the crystalline sulfide solid electrolyte of this embodiment is more likely to exhibit diffraction peaks at 2θ = 20.3 ± 0.5 ° and 29.6 ± 0.6 °. As a result, a crystalline sulfide solid electrolyte having high ionic conductivity is more easily obtained while reducing raw material costs. Here, "not containing metal atoms" not only means that they are not contained at all (i.e., 0% by mass), but also includes cases where they are inevitably mixed in. In this case, the content is 3% by mass or less, 2% by mass or less, 1% by mass or less, 0.5% by mass or less, 0.3% by mass or less, or 0.1% by mass or less based on the total amount of the crystalline sulfide solid electrolyte.

[0060] (Composition) As described above, the crystalline sulfide solid electrolyte of this embodiment contains lithium atoms, phosphorus atoms, sulfur atoms, oxygen atoms, and halogen atoms, and has the two diffraction peaks described above, i.e., diffraction peaks at 2θ = 20.3 ± 0.5 ° and 29.6 ± 0.6 °, and has a composition represented by the following composition formula (1). By having the composition represented by the following composition formula (1), the diffraction peaks at 2θ = 20.3 ± 0.5 ° and 29.6 ± 0.6 ° are more likely to appear, resulting in reduced raw material costs and high ionic conductivity. The types and composition of the atoms constituting the crystalline sulfide solid electrolyte of this embodiment can be confirmed, for example, by an ICP optical emission spectrometer.

[0061] (100-y)(0.5)(Li ３＋２ｚ P (S １－ｘ O ｘ ) ４＋ｚ )+(y)LiX (1)

[0062] In the composition formula (1), x, y, and z satisfy the following conditions: 0.00060≦x≦0.15, 3.0≦y<25.0, and −0.17≦z≦1.5. X represents a halogen atom.

[0063] x represents the substitution rate of oxygen atoms when some sulfur atoms are replaced with oxygen atoms. From the viewpoint of satisfying 0.00060≦x≦0.15, making it easier to exhibit the diffraction peak, thereby reducing raw material costs, and obtaining high ionic conductivity, x is preferably 0.0010 or more, more preferably 0.0030 or more, and even more preferably 0.0050 or more, with the upper limit being preferably 0.12 or less, more preferably 0.085 or less, even more preferably 0.065 or less, and still more preferably 0.045 or less.

[0064] Representative numerical ranges of x are 0.00060 or more and 0.15 or less, 0.00060 or more and 0.12 or less, 0.00060 or more and 0.085 or less, 0.00060 or more and 0.065 or less, 0.00060 or more and 0.045 or less, 0.0010 or more and 0.15 or less, 0.0010 or more and 0.12 or less, 0.0010 or more and 0.085 or less, 0.0010 or more and 0.065 or less, 0.0010 or more and 0.0 Preferred examples thereof include 0.0030 or more and 0.15 or less, 0.0030 or more and 0.12 or less, 0.0030 or more and 0.085 or less, 0.0030 or more and 0.065 or less, 0.0030 or more and 0.045 or less, 0.0050 or more and 0.15 or less, 0.0050 or more and 0.12 or less, 0.0050 or more and 0.085 or less, 0.0050 or more and 0.065 or less, and 0.0050 or more and 0.045 or less.

[0065] The symbol y represents the content of halogen atoms. For convenience, the composition formula (1) is expressed in the form of LiX (lithium halide), but the raw material containing halogen atoms is not limited to lithium halide, and may be, for example, a simple halogen, as will be described later.

[0066] y satisfies 3.0≦y<25.0, and from the viewpoint of making the above-mentioned diffraction peaks more readily manifest, thereby reducing raw material costs, and obtaining high ionic conductivity, is preferably 4.5 or more, more preferably 7.0 or more, even more preferably 9.0 or more, still more preferably 10.5 or more, particularly preferably more than 14.0, and still more particularly preferably 14.5 or more, and the upper limit is preferably 22.0 or less, more preferably 21.0 or less, even more preferably 19.0 or less, and still more preferably 17.0 or less.

[0067] Representative numerical ranges for y are 3.0 or more and less than 25.0, 3.0 or more and less than 22.0, 3.0 or more and less than 21.0, 3.0 or more and less than 19.0, 3.0 or more and less than 17.0, 4.5 or more and less than 25.0, 4.5 or more and less than 22.0, 4.5 or more and less than 21.0, 4.5 or more and less than 19.0, 4.5 or more and less than 17.0, 7.0 or more and less than 25.0, 7.0 or more and less than 22.0, 7.0 or more and less than 21.0, 7.0 or more and less than 19.0, 7.0 or more and less than 17.0, 9.0 or more and less than 25.0, 9.0 or more and less than 22.0, and 9.0 or more and less than 21.0. 0 or less, 9.0 or more and 19.0 or less, 9.0 or more and 17.0 or less, 10.5 or more and less than 25.0, 10.5 or more and 22.0 or less, 10.5 or more and 21.0 or less, 10.5 or more and 19.0 or less, 10.5 or more and 17.0 or less, more than 14.0 and less than 25.0, more than 14.0 and 22.0 or less, more than 14.0 and 21.0 or less, more than 14.0 and 19.0 or less, more than 14.0 and 17.0 or less, 14.5 or more and less than 25.0, 14.5 or more and 22.0 or less, 14.5 or more and 21.0 or less, 14.5 or more and 19.0 or less, and 14.5 or more and 17.0 or less.

[0068] z is Li, which is the basic skeleton of the thiolicon region II crystal structure and the LGPS crystal structure. ３ P.S. ４ z satisfies −0.17≦z≦1.5, and from the viewpoint of making the above-mentioned diffraction peaks more readily apparent, thereby reducing raw material costs, and obtaining high ionic conductivity, z is preferably −0.15 or more, more preferably −0.11 or more, even more preferably −0.080 or more, still more preferably −0.040 or more, and particularly preferably −0.020 or more, with the upper limit being preferably 1.0 or less, more preferably 0.90 or less, even more preferably 0.60 or less, still more preferably 0.40 or less, and particularly preferably 0.20 or less.

[0069] Representative numerical ranges of z are -0.17 or more and 1.5 or less, -0.17 or more and 1.0 or less, -0.17 or more and 0.90 or less, -0.17 or more and 0.60 or less, -0.17 or more and 0.40 or less, -0.17 or more and 0.20 or less, -0.15 or more and 1.5 or less, -0.15 or more and 1.0 or less, -0.15 or more and 0.90 or less, -0.15 or more and 0.60 or less, -0.15 or more and 0.40 or less, -0.15 or more and 0.20 or less, -0.11 or more and 1.5 or less, -0.11 or more and 1.0 or less, -0.11 or more and 0.90 or less, -0.11 or more and 0.60 or less, -0.11 or more and 0.40 or less, -0.11 or more and 0.20 or less, -0.080 Preferred examples thereof include those having a molecular weight of 1.5 or less, -0.080 or more and 1.0 or less, -0.080 or more and 0.90 or less, -0.080 or more and 0.60 or less, -0.080 or more and 0.40 or less, -0.080 or more and 0.20 or less, -0.040 or more and 1.5 or less, -0.040 or more and 1.0 or less, -0.040 or more and 0.90 or less, -0.040 or more and 0.60 or less, -0.040 or more and 0.40 or less, -0.040 or more and 0.20 or less.

[0070] The product of x and y (x × y) is preferably 0.0010 or more, more preferably 0.0050 or more, even more preferably 0.010 or more, still more preferably 0.025 or more, particularly preferably 0.050 or more, and the upper limit is preferably 2.7 or less, more preferably 2.0 or less, even more preferably 1.25 or less, still more preferably 0.75 or less, particularly preferably 0.60 or less, more particularly preferably 0.45 or less, and still more particularly preferably 0.28 or less. As mentioned above, x and y can each take any numerical value selected from the above range, but by adopting x and y such that the product of x and y (x × y) falls within the above range, the x and y will have well-balanced numerical values, which makes it easier to express the diffraction peak and makes it easier to obtain a crystalline sulfide solid electrolyte having high ionic conductivity while reducing raw material costs.

[0071] Representative numerical ranges for the product of x and y (x × y) are 0.0010 or more and 2.7 or less, 0.0010 or more and 2.0 or less, 0.0010 or more and 1.25 or less, 0.0010 or more and 0.75 or less, 0.0010 or more and 0.60 or less, 0.0010 or more and 0.45 or less, 0.0010 or more and 0.28 or less, 0.0050 or more and 2.7 or less, 0.0050 or more and 2.0 or less, 0.0050 or more and 1.25 or less, 0.0050 or more and 0.75 or less, 0.0050 or more and 0.60 or less, 0.0050 or more and 0.45 or less, 0.0050 or more and 0.28 or less, 0.010 or more and 2.7 or less, 0.010 or more and 2.0 or less, 0.010 or more and 0.28 or less. and 1.25 or less, 0.010 or more and 0.75 or less, 0.010 or more and 0.60 or less, 0.010 or more and 0.45 or less, 0.010 or more and 0.28 or less, 0.025 or more and 2.7 or less, 0.025 or more and 2.0 or less, 0.025 or more and 1.25 or less, 0.025 or more and 0.75 or less, 0.025 or more and 0.60 or less, 0.025 or more and 0.45 or less, 0.025 or more and 0.28 or less, 0.050 or more and 2.7 or less, 0.050 or more and 2.0 or less, 0.050 or more and 1.25 or less, 0.050 or more and 0.75 or less, 0.050 or more and 0.60 or less, 0.050 or more and 0.45 or less, and 0.050 or more and 0.28 or less are preferred.

[0072] In the composition formula (1), X represents a halogen atom. The halogen atom is the same as the halogen atom described as a constituent atom of the crystalline sulfide solid electrolyte of this embodiment.

[0073] (solid ３１ P-NMR spectrum) The crystalline sulfide solid electrolyte of this embodiment is a solid ３１ P-NMR measurement revealed that PSO ３ ３－ It is preferable that a peak due to PO is observed at 9.2±5.0 ppm. ４ ３－ Furthermore, there is a peak at 70.3±5.0 ppm due to PS ２ O ２ ３－ It is preferable that a peak due to the above is observed. ３１The method for P-NMR measurement will be explained in the examples. ３１ The peaks measured by P-NMR may fluctuate within a range of ±5.0 ppm, and further within a range of ±4.0 ppm, ±3.0 ppm, or ±2.0 ppm.

[0074] PSO ３ ３－ The peak due to PO ４ ３－ Peaks due to and PS ２ O ２ ３－ The peak due to indicates that at least the crystalline sulfide solid electrolyte of this embodiment has oxygen atoms in its structure. ３１ A crystalline sulfide solid electrolyte having the above peaks in the P-NMR spectrum has oxygen atoms incorporated into its structure, i.e., some of the sulfur atoms are replaced by oxygen atoms, and therefore has two diffraction peaks in X-ray diffraction measurement using the CuKα ray. As a result, higher ionic conductivity can be obtained.

[0075] (Exothermic Peak) The crystalline sulfide solid electrolyte of this embodiment preferably exhibits at least two exothermic peaks in thermogravimetric differential calorimetry (measured at a heating rate of 10° C. / min), with the temperature difference between the peak tops of the two exothermic peaks being 20° C. or more and 110° C. or less. The method for thermogravimetric differential calorimetry in this specification will be described in the examples.

[0076] When the two exothermic peaks are observed in thermogravimetric differential calorimetry, the crystalline sulfide solid electrolyte of this embodiment is likely to exhibit diffraction peaks at 2θ = 20.3 ± 0.5 ° and 29.6 ± 0.6 °. In addition, in this case, when the temperature of the lower peak top of the two exothermic peaks is Tc1 and the temperature of the higher peak top is Tc2, the temperature difference (ΔTc = Tc2 - Tc1) is preferably 20 ° C or more and 110 ° C or less. The lower limit of the temperature difference is preferably 30 ° C or more, more preferably 35 ° C or more, even more preferably 45 ° C or more, even more preferably 50 ° C or more, and particularly preferably 55 ° C or more, and the upper limit is preferably 100 ° C or less, more preferably 95 ° C or less, and even more preferably 90 ° C or less.

[0077] In thermogravimetric differential calorimetry, the peak top temperature (Tc1) of the exothermic peak on the lower temperature side is preferably 180° C. or higher, more preferably 185° C. or higher, even more preferably 190° C. or higher, and still more preferably 195° C. or higher, with the upper limit being preferably 330° C. or lower, more preferably 325° C. or lower, even more preferably 310° C. or lower, and still more preferably 300° C. or lower. The peak top temperature (Tc2) of the exothermic peak on the higher temperature side is preferably 180° C. or higher, more preferably 190° C. or higher, even more preferably 220° C. or higher, still more preferably 240° C. or higher, and particularly preferably 255° C. or higher.

[0078] It can be said that a crystalline sulfide solid electrolyte having diffraction peaks at 2θ = 20.3 ± 0.5 ° and 29.6 ± 0.6 ° is one in which the above two exothermic peaks are easily observed. The observation of these two exothermic peaks means that a crystalline sulfide solid electrolyte, particularly a crystalline sulfide solid electrolyte having a thiolicon region II crystal structure or an LGPS crystal structure that exhibits high ionic conductivity, is easily obtained. Therefore, if the above two exothermic peaks are observed in thermogravimetric differential calorimetry, a crystalline sulfide solid electrolyte having high ionic conductivity can be easily obtained while reducing raw material costs.

[0079] (Ionic Conductivity) The ionic conductivity of the crystalline sulfide solid electrolyte of this embodiment can be 0.85 mS / cm or more, further 1.0 mS / cm or more, 1.5 mS / cm or more, 2.0 mS / cm or more, 2.5 mS / cm or more, 3.0 mS / cm or more, 3.5 mS / cm or more, 4.0 mS / cm or more, 4.4 mS / cm or more, or 5.0 mS / cm or more. Thus, the crystalline sulfide solid electrolyte of this embodiment has high ionic conductivity.

[0080] For example, when the amount of raw material containing halogen atoms used is small, more specifically, when y in the above composition formula (1) is as small as 10.0 or less, the ionic conductivity can be 0.85 mS / cm or more, or even 1.0 mS / cm or more, 1.5 mS / cm or more, or 2.0 mS / cm or more. On the other hand, when the amount of raw material containing halogen atoms used is large, more specifically, when y in the above composition formula (1) is as large as more than 10.0, the ionic conductivity can be 2.0 mS / cm or more, 2.5 mS / cm or more, 3.0 mS / cm or more, 3.5 mS / cm or more, 4.0 mS / cm or more, 4.4 mS / cm or more, or 5.0 mS / cm or more.

[0081] (Crystalline sulfide solid electrolyte of another embodiment) The crystalline sulfide solid electrolyte according to the fourteenth embodiment is a crystalline sulfide solid electrolyte of another embodiment, which contains lithium atoms, phosphorus atoms, sulfur atoms, oxygen atoms, and halogen atoms, and has diffraction peaks at 2θ=20.3±0.5° and 29.6±0.6° in X-ray diffraction measurement using CuKα rays, and ３１ P-NMR measurement revealed that PSO was 39.6±5.0 ppm. ３ ３－ A peak due to the above is observed.

[0082] In another embodiment, the crystalline sulfide solid electrolyte contains lithium atoms, phosphorus atoms, sulfur atoms, oxygen atoms, and halogen atoms, and has a predetermined diffraction peak and a solid state in X-ray diffraction measurement. ３１ The predetermined peaks in the P-NMR measurement are the same as those described above for the crystalline sulfide solid electrolyte of this embodiment. ３１Regarding the predetermined peaks in the P-NMR measurement, PO was detected at 9.2±5.0 ppm. ４ ３－ A peak due to PS was observed at 0.3±5.0 ppm. ２ O ２ ３－ As described above, it is also preferable that the peaks due to lithium atoms, phosphorus atoms, sulfur atoms, oxygen atoms and halogen atoms are observed in the X-ray diffraction measurement. ３１ By having a structure that produces a predetermined peak in P-NMR measurement, high ionic conductivity can be obtained.

[0083] The composition of the crystalline sulfide solid electrolyte of another embodiment includes lithium atoms, phosphorus atoms, sulfur atoms, oxygen atoms, and halogen atoms, has a predetermined diffraction peak, and has a predetermined PSO ３ ３－ There are no particular limitations as long as a peak due to the above is observed. ３１ From the viewpoint of facilitating the appearance of a predetermined peak in P-NMR measurement, it is preferable to have a composition represented by the above composition formula (1).

[0084] [Applications] The crystalline sulfide solid electrolyte of the present embodiment has high ionic conductivity while reducing raw material costs, and has excellent battery performance. Therefore, it is suitable for use in, for example, an electrode composite in combination with an electrode active material, or in a lithium ion battery.

[0085] When the sulfide solid electrolyte of this embodiment is used in a lithium ion battery, it may be used in the positive electrode layer, the negative electrode layer, or the electrolyte layer. When used in the positive electrode layer, it can be used as an electrode composite containing the crystalline sulfide solid electrolyte of this embodiment and a positive electrode active material, and when used in the negative electrode layer, it can be used as an electrode composite containing the crystalline sulfide solid electrolyte of this embodiment and a negative electrode active material. Furthermore, the crystalline sulfide solid electrolyte may be used as it is in the electrolyte layer.

[0086] [Electrode Mixture] As described above, the electrode mixture contains the crystalline sulfide solid electrolyte of the present embodiment and an electrode active material. Depending on whether the electrode mixture is used for a positive electrode or a negative electrode, a positive electrode active material or a negative electrode active material is adopted as the electrode active material.

[0087] The positive electrode active material can be any material that can promote a battery chemical reaction involving the movement of lithium ions due to atoms that are used to exhibit ionic conductivity, preferably lithium atoms, in relation to the negative electrode active material. Examples of such positive electrode active materials that can insert and extract lithium ions include oxide-based positive electrode active materials and sulfide-based positive electrode active materials.

[0088] Oxide-based positive electrode active materials include LMO (lithium manganese oxide), LCO (lithium cobalt oxide), NMC (lithium nickel manganese cobalt oxide), NCA (lithium nickel cobalt aluminate), LNCO (lithium nickel cobalt oxide), and olivine-type compounds (LiMeNPO ４ , Me=Fe, Co, Ni, Mn) and other lithium-containing transition metal composite oxides are preferred. Examples of sulfide-based positive electrode active materials include titanium sulfide (TiS ２ ), molybdenum sulfide (MoS ２ ), iron sulfide (FeS, FeS ２ ), copper sulfide (CuS), nickel sulfide (Ni ３ S ２ In addition to the above positive electrode active materials, niobium selenide (NbSe) ３ The positive electrode active material may be used alone or in combination of two or more.

[0089] The negative electrode active material can be any atom capable of exhibiting ionic conductivity, preferably a metal capable of forming an alloy with lithium atoms, its oxide, or an alloy of the metal with lithium atoms, as long as it can promote the battery chemical reaction involving the transfer of lithium ions due to lithium atoms. As such a negative electrode active material capable of intercalating and deintercalating lithium ions, any material known in the battery field as a negative electrode active material can be used without limitation. For example, when constructing a lithium-ion battery, such a negative electrode active material can be used. Examples of such a negative electrode active material include silicon-based active materials such as Si, Si alloys, and silicon oxide; carbon-based active materials such as graphite and hard carbon; various oxide-based active materials such as lithium titanate; metals capable of forming alloys with metallic lithium or metallic lithium, such as metallic lithium, metallic indium, metallic aluminum, metallic silicon, and metallic tin, oxides of these metals, and alloys of these metals with metallic lithium.

[0090] The electrode active material may have a coating layer on its surface. Examples of materials for forming the coating layer include ion conductors such as nitrides, oxides, or composites of atoms that exhibit ionic conductivity in the sulfide solid electrolyte, preferably lithium atoms. Specifically, lithium nitride (Li ３ N), Li ４ GeO ４ The main structure is, for example, Li ４－２ｘ Zn ｘ GeO ４ Conductors having a lysicone-type crystal structure such as Li ３ P.O. ４ For example, Li ４－ｘ Ge １－ｘ P ｘ S ４ Conductors having a thiolicon-type crystal structure such as La ２／３－ｘ Li ３ｘ TiO ３ Conductors having a perovskite crystal structure such as LiTi ２ (P.O. ４ ) ３ Conductors having a NASICON type crystal structure such as Li ｙTi ３－ｙ O ４ (0<y<3), Li ４ Ti ５ O １２ Lithium titanate (LTO), LiNbO ３ , LiTaO ３ Lithium metal oxides of metals belonging to Group 5 of the periodic table, such as Li ２ Alumni ２ O ３ -P ２ O ５ system, Li ２ Alumni ２ O ３ -ZnO-based, Li ２ O-Al ２ O ３ -SiO ２ -P ２ O ５ -TiO ２ Examples of suitable conductors include oxide-based conductors such as those based on ZnO.

[0091] An electrode active material having a coating layer can be obtained, for example, by applying a solution containing various atoms constituting the material forming the coating layer to the surface of the electrode active material and then baking the electrode active material after application, preferably at 200°C to 400°C. Here, the solution containing various atoms may be, for example, a solution containing alkoxides of various metals such as lithium ethoxide, titanium isopropoxide, niobium isopropoxide, or tantalum isopropoxide. In this case, the solvent may be an alcoholic solvent such as ethanol or butanol; an aliphatic hydrocarbon solvent such as hexane, heptane, or octane; or an aromatic hydrocarbon solvent such as benzene, toluene, or xylene. The application may be performed by immersion, spray coating, or the like.

[0092] From the viewpoint of improving production efficiency and battery performance, the firing temperature is preferably 200°C or higher and 400°C or lower, more preferably 250°C or higher and 390°C or lower, and the firing time is usually about 1 minute to 10 hours, preferably 10 minutes to 4 hours.

[0093] The coverage of the coating layer is preferably 90% or more, more preferably 95% or more, and even more preferably 100% based on the surface area of ​​the electrode active material, i.e., the entire surface is preferably covered. The thickness of the coating layer is preferably 1 nm or more, more preferably 2 nm or more, and the upper limit is preferably 30 nm or less, more preferably 25 nm or less. The thickness of the coating layer can be measured by cross-sectional observation using a transmission electron microscope (TEM), and the coverage can be calculated from the thickness of the coating layer, elemental analysis value, and BET specific surface area.

[0094] (Other Components) The electrode mixture may contain other components such as a conductive material, a binder, etc. in addition to the crystalline sulfide solid electrolyte and electrode active material of the present embodiment. That is, the electrode mixture may contain other components such as a conductive material, a binder, etc. in addition to the crystalline sulfide solid electrolyte and electrode active material of the present embodiment. When mixing the crystalline sulfide solid electrolyte and the electrode active material, the other components such as a conductive material, a binder, etc. may be added to and mixed with the crystalline sulfide solid electrolyte and the electrode active material. From the viewpoint of improving battery performance by improving electronic conductivity, examples of the conductive material include carbon-based materials such as artificial graphite, graphite carbon fiber, resin-calcined carbon, pyrolytic vapor-grown carbon, coke, mesocarbon microbeads, furfuryl alcohol resin-calcined carbon, polyacene, pitch-based carbon fiber, vapor-grown carbon fiber, natural graphite, and non-graphitizable carbon.

[0095] The use of a binder improves the strength of the produced positive and negative electrodes. The binder is not particularly limited as long as it can impart functions such as binding property and flexibility, and examples thereof include fluorine-based polymers such as polytetrafluoroethylene and polyvinylidene fluoride, thermoplastic elastomers such as butylene rubber and styrene-butadiene rubber, acrylic resins, acrylic polyol resins, polyvinyl acetal resins, polyvinyl butyral resins, and silicone resins.

[0096] The blending ratio (mass ratio) of the electrode active material to the crystalline sulfide solid electrolyte in the electrode mixture is preferably 99.5:0.5 to 40:60, more preferably 99:1 to 50:50, and even more preferably 98:2 to 60:40, in consideration of improving battery performance and production efficiency.

[0097] When a conductive material is contained, the content of the conductive material in the electrode mixture is not particularly limited, but in consideration of improving battery performance and manufacturing efficiency, it is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 1.5% by mass or more, with the upper limit being preferably 10% by mass or less, preferably 8% by mass or less, and even more preferably 5% by mass or less. Furthermore, when a binder is contained, the content of the binder in the electrode mixture is not particularly limited, but in consideration of improving battery performance and manufacturing efficiency, it is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, with the upper limit being preferably 20% by mass or less, preferably 15% by mass or less, and even more preferably 10% by mass or less.

[0098] [Lithium-ion battery] The crystalline sulfide solid electrolyte of this embodiment can also be used in a lithium-ion battery as described above. For example, the lithium-ion battery can include at least one selected from the sulfide solid electrolyte of this embodiment and the electrode composite.

[0099] The lithium ion battery is not particularly limited in its configuration as long as it contains the crystalline sulfide solid electrolyte of the present embodiment described above and an electrode composite containing the same, and has the configuration of a commonly used lithium ion battery. It may be any.

[0100] The lithium ion battery preferably includes, for example, a positive electrode layer, a negative electrode layer, an electrolyte layer, and a current collector. The positive electrode layer and the negative electrode layer preferably use an electrode mixture containing the crystalline sulfide solid electrolyte of the present embodiment, and the electrolyte layer preferably uses the crystalline sulfide solid electrolyte of the present embodiment.

[0101] The current collector may be a known material, for example, a layer of Au or the like coated with a material that reacts with the solid electrolyte, such as Au, Pt, Al, Ti, or Cu.

[0102] (Method for producing crystalline sulfide solid electrolyte) A method for producing the crystalline sulfide solid electrolyte of this embodiment will be described. The crystalline sulfide solid electrolyte of this embodiment can be obtained by a production method including mixing raw material components containing, for example, lithium atoms, sulfur atoms, phosphorus atoms, oxygen atoms, and halogen atoms.

[0103] (Raw material containing substance) The raw material containing substance contains lithium atoms, phosphorus atoms, sulfur atoms, oxygen atoms, and halogen atoms. More specifically, the raw material containing substance contains one or more kinds of atoms selected from the group consisting of these atoms (hereinafter also referred to as "raw material"), and preferably contains two or more kinds of raw materials.

[0104] The raw materials include, for example, lithium sulfide; diphosphorus trisulfide (P ２ S ３ ), diphosphorus pentasulfide (P ２ S ５ and phosphorus sulfides such as methyl phosphate, ...

[0105] Among the above, lithium sulfide and diphosphorus trisulfide (P ２ S ３ ), diphosphorus pentasulfide (P ２ S ５ Among phosphorus sulfides, phosphorus pentasulfide (P ２ S ５ ) is preferred.

[0106] Preferred examples of the raw material include substances containing halogen atoms. For example, lithium halides such as lithium fluoride, lithium chloride, lithium bromide, and lithium iodide; fluorine (F ２ ), chlorine (Cl ２ ), bromine (Br ２ ), iodine (I ２) and other simple halogen atoms are typically preferred.

[0107] Furthermore, preferable raw materials include substances containing oxygen atoms. For example, diphosphorus pentoxide (P ２ O ５ ), lithium oxide (Li ２ Representative examples of preferred cations include diphosphorus pentoxide (P ２ O ５ ) is preferred.

[0108] The raw material is a substance containing at least one atom selected from lithium atoms, phosphorus atoms, sulfur atoms, oxygen atoms, and halogen atoms, such as various phosphorus fluorides (PF ３ , P.F. ５ ), various phosphorus chlorides (PCl ３ , PCl ５ , P ２ Cl ４ ), various phosphorus bromides (PBr ３ , PBr ５ ), various phosphorus iodides (PI ３ , P ２ I ４ ) and the like; phosphorus halides such as thiophosphoryl fluoride (PSF ３ ), thiophosphoryl chloride (PSCl ３ ), thiophosphoryl bromide (PSBr ３ ), thiophosphoryl iodide (PSI ３ ), thiophosphoryl fluoride dichloride (PSCl ２ F), thiophosphoryl fluoride dibromide (PSBr ２ Thiophosphoryl halides such as lithium oxide, lithium hydroxide, lithium carbonate, and the like; alkali metal sulfides such as sodium sulfide, potassium sulfide, rubidium sulfide, and cesium sulfide; silicon sulfide, germanium sulfide, boron sulfide, gallium sulfide, and tin sulfide (SnS, SnS ２metal sulfides such as aluminum sulfide and zinc sulfide; phosphate compounds such as sodium phosphate and lithium phosphate; halides of alkali metals other than lithium such as sodium halides such as sodium iodide, sodium fluoride, sodium chloride and sodium bromide; metal halides such as aluminum halides, silicon halides, germanium halides, arsenic halides, selenium halides, tin halides, antimony halides, tellurium halides and bismuth halides; phosphorus oxychloride (POCl ３ ), phosphorus oxybromide (POBr ３ and the like.

[0109] Also, P.S. ４ Li containing structure ３ P.S. ４ , Li ７ P ３ S １１ It is also possible to use as a raw material substances that act as solid electrolytes, such as Li ３ P.S. ４ When using as a raw material, for example, Li is first obtained by using lithium sulfide and diphosphorus pentasulfide. ３ P.S. ４ may be prepared by manufacturing or the like and used as a raw material.

[0110] The raw materials such as lithium sulfide are preferably in the form of particles. This facilitates mixing of the raw materials, which makes it easier to produce a crystalline sulfide solid electrolyte. The average particle size (D ５０ In consideration of the reaction of the raw materials, handling, etc., the average particle size (D) is preferably, for example, 0.1 μm or more and 1000 μm or less, 0.5 μm or more and 100 μm or less, or 1 μm or more and 20 μm or less. ５０ ) is the particle size at which 50% (volume basis) of the total particle size is reached when the particle sizes are sequentially added together starting from the smallest particle size when an integrated particle size distribution curve is drawn, and the volume distribution refers to an average particle size that can be measured using, for example, a laser diffraction / scattering particle size distribution measuring device.

[0111] The crystalline sulfide solid electrolyte of this embodiment may be prepared by appropriately combining the above raw materials, preferably to obtain a composition represented by the above composition formula (1). The composition contains lithium atoms, phosphorus atoms, sulfur atoms, oxygen atoms, and halogen atoms, and facilitates the expression of the above diffraction peaks, thereby reducing raw material costs and facilitating the attainment of high ionic conductivity. The composition of the crystalline sulfide solid electrolyte of this embodiment represented by the above composition formula (1) can be confirmed using an ICP optical emission spectrometer as described above. However, since the composition contains oxygen atoms, there may be a discrepancy between the actual composition and the measured value. In such cases, it has been confirmed that there is almost no discrepancy between the substances used as raw materials and their blending ratios and the composition calculated from the substances and their blending ratios. Therefore, the composition can also be considered as a composition calculated from the substances used as raw materials and their blending ratios.

[0112] When lithium sulfide and diphosphorus pentasulfide are used as raw materials, the ratio of lithium sulfide to the total of lithium sulfide and diphosphorus pentasulfide is, from the viewpoint of obtaining higher ionic conductivity, preferably 45.0 mol% or more, more preferably 60.0 mol% or more, even more preferably 67.0 mol% or more, still more preferably 70.0 mol% or more, and particularly preferably 73.0 mol% or more, with the upper limit being preferably 85.0 mol% or less, more preferably 80.0 mol% or less, even more preferably 78.0 mol% or less, and still more preferably 76.0 mol% or less. Representative numerical ranges are preferably 45.0 to 85.0 mol%, 55.0 to 85.0 mol%, 65.0 to 85.0 mol%, 67.0 to 85.0 mol%, 70.0 to 85.0 mol%, 73.0 to 85.0 mol%, 55.0 to 78.0 mol%, 65.0 to 78.0 mol%, 67.0 to 78.0 mol%, 70.0 to 78.0 mol%, 73.0 to 78.0 mol%, 70.0 to 76.0 mol%, and 73.0 to 76.0 mol%.

[0113] When the raw material content includes diphosphorus pentoxide as a raw material containing diphosphorus pentasulfide and oxygen atoms, the ratio of diphosphorus pentoxide to the total of these is, from the viewpoint of achieving higher ionic conductivity and reducing raw material costs, preferably 0.1 mol% or more, more preferably 0.3 mol% or more, even more preferably 0.5 mol% or more, and still more preferably 0.8 mol% or more, with the upper limit being preferably 22.0 mol% or less, more preferably 18.0 mol% or less, even more preferably 12.0 mol% or less, still more preferably 8.0 mol% or less, and particularly preferably 5.0 mol% or less. Representative numerical ranges are preferably 0.1 to 22.0 mol%, 0.1 to 18.0 mol%, 0.1 to 12.0 mol%, 0.1 to 8.0 mol%, 0.1 to 5.0 mol%, 0.3 to 22.0 mol%, 0.3 to 18.0 mol%, 0.3 to 12.0 mol%, 0.3 to 8.0 mol%, 0.3 to 5.0 mol%, 0.5 to 22.0 mol%, 0.5 to 18.0 mol%, 0.5 to 12.0 mol%, 0.5 to 8.0 mol%, 0.5 to 5.0 mol%, 0.8 to 22.0 mol%, 0.8 to 18.0 mol%, 0.8 to 12.0 mol%, 0.8 to 8.0 mol%, 0.8 to 5.0 mol%.

[0114] When the raw material content includes lithium sulfide, diphosphorus pentasulfide, lithium halide, a raw material containing an oxygen atom, and other raw materials used as needed, the content of lithium sulfide and diphosphorus pentasulfide relative to the total of these is preferably 60.0 mol% or more, more preferably 65.0 mol% or more, even more preferably 70.0 mol% or more, still more preferably 80.0 mol% or more, and the upper limit is preferably less than 100 mol%, more preferably 95.0 mol% or less, even more preferably 90.0 mol% or less, and still more preferably 85.0 mol% or less. Furthermore, in a case where lithium sulfide, diphosphorus pentasulfide, lithium halide, a raw material containing an oxygen atom, and other raw materials used as necessary are included, the content of lithium halide relative to the total of lithium sulfide, diphosphorus pentasulfide, lithium halide, and the raw material containing an oxygen atom is preferably 1.0 mol% or more, more preferably 3.0 mol% or more, even more preferably 5.0 mol% or more, still more preferably 8.0 mol% or more, and the upper limit is preferably 22.0 mol% or less, more preferably 21.0 mol% or less, even more preferably 20.0 mol% or less, still more preferably 19.0 mol% or less, and particularly preferably 17.5 mol% or less.

[0115] (Mixing) The mixing of raw material containing lithium atoms, sulfur atoms, phosphorus atoms, oxygen atoms, and halogen atoms is not particularly limited as long as the raw materials can be mixed. For example, the mixing can be performed using a pulverizer, mixer, stirrer, etc. Using a pulverizer will result in pulverization of the raw materials, but mixing will also occur at the same time. Mixing of the raw materials can also occur using a mixer or stirrer. Therefore, it can be said that the crystalline sulfide solid electrolyte of this embodiment can be preferably produced by stirring, mixing, pulverizing, or a combination of any of these processes using two or more raw materials selected from substances containing at least one atom of lithium atoms, sulfur atoms, phosphorus atoms, oxygen atoms, and halogen atoms.

[0116] Examples of the stirrer or mixer include a mechanical stirring mixer that is equipped with stirring blades in a reaction vessel and can stir (also referred to as mixing by stirring or stirring and mixing). Examples of the mechanical stirring mixer include a high-speed stirring mixer and a double-arm mixer. Examples of the high-speed stirring mixer include a vertical-axis rotary mixer and a horizontal-axis rotary mixer, and either type of mixer may be used.

[0117] Examples of the shape of the stirring blade used in the mechanical stirring mixer include blade type, arm type, anchor type, paddle type, full zone type, ribbon type, multi-stage blade type, double arm type, shovel type, double-shaft blade type, flat blade type, C-type blade type, etc., and from the viewpoint of promoting the reaction of the raw materials more efficiently, the shovel type, flat blade type, C-type blade type, anchor type, paddle type, full zone type, etc. are preferred, with the anchor type, paddle type, and full zone type being more preferred.

[0118] When a mechanical stirring mixer is used, the rotation speed of the stirring blades can be adjusted appropriately depending on the volume of the fluid in the reaction vessel, the temperature, the shape of the stirring blades, etc., and is not particularly limited. However, it is usually sufficient to set the rotation speed at about 5 rpm or more and 400 rpm or less. From the viewpoint of more efficiently promoting the reaction of the raw materials, the rotation speed is preferably 10 rpm or more and 300 rpm or less, more preferably 15 rpm or more and 250 rpm or less, and even more preferably 20 rpm or more and 200 rpm or less.

[0119] The temperature conditions when mixing is performed using a mixer or the like are not particularly limited, and are, for example, usually −30 to 120° C., preferably −10 to 100° C., more preferably 0 to 80° C., and even more preferably 10 to 60° C. The mixing time is usually 0.1 to 500 hours, and from the viewpoint of achieving a more uniform dispersion state of the raw materials and promoting the reaction, is preferably 1 to 450 hours, more preferably 10 to 425 hours, even more preferably 20 to 400 hours, and still more preferably 40 to 375 hours.

[0120] The method of mixing with pulverization using a pulverizer has traditionally been adopted as a solid-phase method (mechanical milling method). As the pulverizer, for example, a media-type pulverizer using a pulverization medium can be used. Media-type pulverizers are broadly classified into container-driven pulverizers and media-agitation pulverizers. Examples of container-driven pulverizers include agitation tanks, pulverization tanks, or combinations thereof, such as ball mills and bead mills. Examples of media-agitation pulverizers include impact pulverizers such as cutter mills, hammer mills, and pin mills; tower-type pulverizers such as tower mills; agitation tank pulverizers such as attritors, aquamizers, and sand grinders; flow-through tank pulverizers such as Viscomill and pearl mills; flow-through pipe pulverizers; annular pulverizers such as Coball mills; continuous dynamic pulverizers; and various pulverizers such as single-shaft or multi-shaft kneaders. Among these, considering the ease of adjusting the particle size of the resulting sulfide, the ball mills and bead mills exemplified as container-driven pulverizers are preferred, and planetary pulverizers are particularly preferred.

[0121] These pulverizers can be appropriately selected depending on the desired scale, etc. For relatively small scales, container-driven pulverizers such as ball mills and bead mills can be used, while for large scales or mass production, other types of pulverizers may be used.

[0122] Furthermore, as will be described later, when the mixture is in a liquid state involving a liquid such as a solvent or in a slurry state during mixing, a wet mill that can handle wet milling is preferred. Typical examples of wet mills include wet bead mills, wet ball mills, and wet vibration mills. Wet bead mills that use beads as milling media are preferred because they allow for free adjustment of milling conditions and are easily adaptable to smaller particle sizes. Dry mills, such as dry media mills (e.g., dry bead mills, dry ball mills, and dry vibration mills) and dry non-media mills (e.g., jet mills), can also be used.

[0123] Furthermore, when the material to be mixed is in a liquid state or a slurry state, a flow-through mill that can perform a circulation operation to circulate the material as needed can also be used. Specifically, a mill that circulates the material between a mill (pulverizing mixer) that pulverizes the slurry and a temperature holding tank (reaction vessel) can be used.

[0124] When using a ball mill or bead mill, the rotation speed varies depending on the scale of the treatment and cannot be generalized, but is usually 10 rpm or more, preferably 20 rpm or more, more preferably 50 rpm or more, and even more preferably 100 rpm or more. The upper limit is usually 1,000 rpm or less, preferably 900 rpm or less, more preferably 800 rpm or less, even more preferably 700 rpm or less, and even more preferably 500 rpm or less. The milling time varies depending on the scale of the treatment and cannot be generalized, but is usually 0.5 hours or more, preferably 1 hour or more, more preferably 5 hours or more, even more preferably 10 hours or more, even more preferably 20 hours or more, and particularly preferably 25 hours or more. The upper limit is usually 100 hours or less, preferably 72 hours or less, and more preferably 48 hours or less. When the milling time is within the above range, the atoms contained in the raw material, especially oxygen atoms and halogen atoms, are more efficiently and uniformly dispersed, making it easier to obtain high ionic conductivity.

[0125] By selecting the size and material of the medium (beads or balls) used, the rotor rotation speed, time, and the like, it is possible to perform mixing, stirring, pulverization, or a combination of these processes, and it is possible to adjust the particle size, etc. of the resulting crystalline sulfide solid electrolyte.

[0126] (Solvent) When mixing the raw materials, a solvent may be added to the raw materials and mixed in. As the solvent, various solvents widely known as organic solvents may be used.

[0127] As the solvent, a wide variety of solvents that have conventionally been used in the production of solid electrolytes can be used, and examples thereof include hydrocarbon solvents such as aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents.

[0128] Examples of aliphatic hydrocarbons include hexane, pentane, 2-ethylhexane, heptane, octane, decane, undecane, dodecane, and tridecane. Examples of alicyclic hydrocarbons include cyclohexane and methylcyclohexane. Examples of aromatic hydrocarbon solvents include benzene, toluene, xylene, mesitylene, ethylbenzene, tert-butylbenzene, trifluoromethylbenzene, and nitrobenzene.

[0129] In addition to the above hydrocarbon solvents, solvents containing heteroatoms such as atoms other than carbon and hydrogen atoms, for example, nitrogen, oxygen, sulfur, and halogen atoms, are also suitable. Such solvents have the property of easily forming complexes with raw materials containing lithium, phosphorus, sulfur, oxygen, and halogen atoms (hereinafter, such solvents are also referred to as "complexing agents"), and are useful in that they facilitate the retention of halogen atoms within the structure of the sulfide solid electrolyte, thereby achieving higher ionic conductivity. Preferred examples of such complexing agents include ether solvents, ester solvents, and alcohol solvents, aldehyde solvents, and ketone solvents containing oxygen atoms as heteroatoms. Furthermore, when using such complexing agents, it is possible to proceed with the reaction of the raw materials using a mixer or agitator without using a mill.

[0130] Preferred examples of the ether solvent include aliphatic ethers such as dimethyl ether, diethyl ether, tert-butyl methyl ether, dimethoxymethane, dimethoxyethane, diethylene glycol dimethyl ether (diglyme), triethylene oxide glycol dimethyl ether (triglyme), diethylene glycol, and triethylene glycol; alicyclic ethers such as ethylene oxide, propylene oxide, tetrahydrofuran, tetrahydropyran, dimethoxytetrahydrofuran, cyclopentyl methyl ether, and dioxane; heterocyclic ethers such as furan, benzofuran, and benzopyran; and aromatic ethers such as methyl phenyl ether (anisole), ethyl phenyl ether, dibenzyl ether, and diphenyl ether.

[0131] Preferred examples of the ester solvent include methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, and isopropyl acetate; aliphatic esters such as methyl propionate, ethyl propionate, dimethyl oxalate, diethyl oxalate, dimethyl malonate, diethyl malonate, dimethyl succinate, and diethyl succinate; alicyclic esters such as methyl cyclohexanecarboxylate, ethyl cyclohexanecarboxylate, and dimethyl cyclohexanedicarboxylate; heterocyclic esters such as methyl pyridinecarboxylate, methyl pyrimidinecarboxylate, acetolactone, propiolactone, butyrolactone, and valerolactone; and aromatic esters such as methyl benzoate, ethyl benzoate, dimethyl phthalate, diethyl phthalate, butyl benzyl phthalate, dicyclohexyl phthalate, trimethyl trimellitate, and triethyl trimellitate.

[0132] Preferred examples of the solvent include alcohol solvents such as ethanol and butanol; aldehyde solvents such as formaldehyde, acetaldehyde and dimethylformamide; and ketone solvents such as acetone and methyl ethyl ketone.

[0133] Examples of solvents containing a nitrogen atom as a heteroatom include solvents having a nitrogen atom-containing group such as an amino group, an amide group, a nitro group, or a nitrile group. For example, preferred examples of solvents having an amino group include aliphatic amines such as ethylenediamine, diaminopropane, dimethylethylenediamine, diethylethylenediamine, dimethyldiaminopropane, tetramethyldiaminomethane, tetramethylethylenediamine (TMEDA), and tetramethyldiaminopropane (TMPDA); alicyclic amines such as cyclopropanediamine, cyclohexanediamine, and bisaminomethylcyclohexane; heterocyclic amines such as isophoronediamine, piperazine, dipiperidylpropane, and dimethylpiperazine; and aromatic amines such as phenyldiamine, tolylenediamine, naphthalenediamine, methylphenylenediamine, dimethylnaphthalenediamine, dimethylphenylenediamine, tetramethylphenylenediamine, and tetramethylnaphthalenediamine. Preferred examples of solvents containing a nitrogen atom include nitrile solvents such as acetonitrile and acrylonitrile; and solvents containing a nitrogen atom such as dimethylformamide, nitrobenzene, and dimethylacetamide.

[0134] Preferred examples of solvents containing a halogen atom as a heteroatom include chloroform, carbon tetrachloride, dichloromethane, chlorobenzene, dichlorobenzene, trifluoromethylbenzene, chlorotoluene, bromobenzene, etc. Preferred examples of solvents containing a sulfur atom include dimethyl sulfoxide, carbon disulfide, etc.

[0135] When a solvent is used, the amount of the solvent used is preferably 100 mL or more, more preferably 200 mL or more, even more preferably 250 mL or more, and still more preferably 300 mL or more per kg of the total amount of the raw materials, and the upper limit is preferably 3000 mL or less, more preferably 2500 mL or less, even more preferably 2000 mL or less, and still more preferably 1550 mL or less. When the amount of the solvent used is within the above range, the raw materials can be reacted efficiently.

[0136] (Drying) When mixing is performed using a solvent, the method may include drying the fluid (usually a slurry) obtained by mixing. When a complexing agent is used as a solvent, the sulfide solid electrolyte is obtained by removing the complexing agent from a complex containing the complexing agent. When a complexing agent and a solvent are used in combination, the complexing agent is removed from a complex containing the complexing agent and the solvent is removed. When a solvent other than a complexing agent is used, the solvent is removed to obtain the sulfide solid electrolyte.

[0137] The fluid obtained by mixing can be dried at a temperature depending on the type of solvent. For example, drying can be performed at a temperature equal to or higher than the boiling point of the complexing agent. Furthermore, drying can be performed under reduced pressure (vacuum drying) using a vacuum pump or the like at a temperature typically between 5 and 100°C, preferably between 10 and 85°C, more preferably between 15 and 70°C, and even more preferably around room temperature (e.g., 23°C) (e.g., about room temperature ±5°C), thereby volatilizing the complexing agent and any solvent used as needed.

[0138] Drying may be performed by filtering the fluid using a glass filter or the like, by solid-liquid separation by decantation, or by solid-liquid separation using a centrifuge or the like. When a solvent other than a complexing agent is used, a sulfide solid electrolyte can be obtained by solid-liquid separation. When a complexing agent is used as the solvent, solid-liquid separation is performed, and then drying is performed under the above-mentioned temperature conditions to remove the complexing agent incorporated into the complex. Specifically, solid-liquid separation is performed by transferring the fluid to a container, and after the sulfide (or the complex if a complexing agent is included (which may also be referred to as a precursor of the sulfide solid electrolyte)) is precipitated, decantation is performed to remove the supernatant complexing agent and solvent, or filtration using a glass filter with a pore size of about 10 to 200 μm, preferably 20 to 150 μm, for example.

[0139] Drying may be carried out after mixing and before the hydrogen treatment described below, or may be carried out after the hydrogen treatment.

[0140] The sulfide solid electrolyte obtained by the above mixing, or the sulfide solid electrolyte obtained by removing the solvent by the above drying when a solvent is used, exhibits ionic conductivity due to lithium atoms. The sulfide solid electrolyte obtained by the above mixing is basically an amorphous sulfide solid electrolyte (glass component) unless it is mixed by pulverizing using a pulverizer to the extent that it crystallizes, for example.

[0141] The sulfide solid electrolyte obtained by the above-mentioned mixing may be an amorphous sulfide solid electrolyte (glass component) or a crystalline sulfide solid electrolyte, and can be appropriately selected as desired. When producing a crystalline sulfide solid electrolyte, the amorphous sulfide solid electrolyte obtained by the above-mentioned mixing can be heated to produce a crystalline sulfide solid electrolyte. The sulfide solid electrolyte may also include a crystalline sulfide solid electrolyte in which an amorphous component (glass component) is formed on the surface thereof as a result of performing a process such as pulverization described below to adjust the particle size of the crystalline sulfide solid electrolyte powder. Therefore, sulfide solid electrolytes containing an amorphous component include amorphous sulfide solid electrolytes and crystalline sulfide solid electrolytes in which an amorphous component is formed on the surface thereof.

[0142] (Heating) When producing the crystalline sulfide solid electrolyte of this embodiment, heating may be further included. If an amorphous sulfide solid electrolyte (glass component) is obtained by the above-mentioned mixing, a crystalline sulfide solid electrolyte can be obtained by heating. Also, if a crystalline sulfide solid electrolyte is obtained, a crystalline sulfide solid electrolyte with improved crystallinity can be obtained. In either case, heating can convert the resulting sulfide solid electrolyte into a crystalline sulfide solid electrolyte, thereby improving ionic conductivity. Furthermore, if a complexing agent is used as a solvent during mixing, a complex containing the complexing agent is formed. However, even if the complexing agent is removed from the complex by heating without the above-mentioned drying, a sulfide solid electrolyte can be obtained. Depending on the heating conditions, the sulfide solid electrolyte can be made amorphous or crystalline.

[0143] The heating temperature may be determined depending on the structure of the crystalline sulfide solid electrolyte. Specifically, an amorphous sulfide solid electrolyte corresponding to the crystalline sulfide solid electrolyte to be obtained is subjected to differential thermal analysis (DTA) using a differential thermal analyzer (DTA device) at a temperature increase condition of 10 ° C. / min. The temperature is preferably set to 5 ° C. or higher, more preferably 10 ° C. or higher, and even more preferably 20 ° C. or higher, starting from the peak top temperature of the exothermic peak observed on the lowest temperature side. The upper limit is not particularly limited, but may be about 40 ° C. or lower. By setting the temperature range as described above, a crystalline sulfide solid electrolyte can be obtained more efficiently and reliably. The heating temperature for obtaining a crystalline sulfide solid electrolyte cannot be generally specified because it varies depending on the composition and structure of the crystalline sulfide solid electrolyte to be obtained, but is typically preferably 130 ° C. or higher, more preferably 135 ° C. or higher, and even more preferably 140 ° C. or higher. The upper limit is not particularly limited, but is preferably 300 ° C. or lower, more preferably 250 ° C. or lower, and even more preferably 200 ° C. or lower.

[0144] The heating time is not particularly limited as long as it is a time that allows a desired amorphous sulfide solid electrolyte or crystalline sulfide solid electrolyte to be obtained, but is, for example, preferably 1 minute or more, more preferably 10 minutes or more, even more preferably 30 minutes or more, and even more preferably 1 hour or more. The upper limit of the heating time is not particularly limited, but is preferably 24 hours or less, more preferably 10 hours or less, even more preferably 5 hours or less, and even more preferably 3 hours or less.

[0145] Furthermore, heating is preferably carried out in an inert gas atmosphere (e.g., a nitrogen atmosphere or an argon atmosphere) or a reduced pressure atmosphere (particularly in a vacuum). For example, an inert gas atmosphere containing a certain concentration of hydrogen may be used. This is because deterioration (e.g., oxidation) of the crystalline sulfide solid electrolyte can be prevented. The heating method is not particularly limited, and examples include methods using a hot plate, a vacuum heating device, an argon gas atmosphere furnace, and a firing furnace. Furthermore, industrially, a horizontal dryer or a horizontal vibration fluidized dryer having a heating means and a feeding mechanism can also be used, and the method may be selected depending on the amount of heat to be processed.

[0146] The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples in any way.

[0147] (Measurement of Ion Conductivity) In the present example, the measurement of ion conductivity was carried out as follows. A 10 mm diameter (cross-sectional area S: 0.785 cm ) sample was taken from the crystalline solid electrolyte obtained in the examples and comparative examples. ２ ), and a height (L) of 0.1 to 0.3 cm were molded into a circular pellet to prepare a sample. Electrode terminals were attached to the top and bottom of the sample, and measurements were made at 25°C using an AC impedance method (frequency range: 7 MHz to 0.1 Hz, amplitude: 10 mV) to obtain a Cole-Cole plot. The real part Z' (Ω) at the point where -Z'' (Ω) is minimum near the right end of the arc observed in the high-frequency region was taken as the bulk resistance R (Ω) of the electrolyte, and the ionic conductivity σ (S / cm) was calculated according to the following formula: R = ρ (L / S) σ = 1 / ρ

[0148] (X-ray Diffraction Measurement (Powder XRD Diffraction Measurement)) Powder X-ray diffraction (XRD) measurement was carried out as follows. The powder of the solid electrolyte produced in each Example and Comparative Example was filled into a groove with a diameter of 20 mm and a depth of 0.2 mm, and leveled with glass to prepare a sample. This sample was sealed with a Kapton film for XRD and measured without being exposed to air. Measurement was carried out using a powder X-ray diffractometer ("D2 PHASER (model number)", manufactured by BRUKER Japan Co., Ltd.) under the following conditions. Tube voltage: 30 kV Tube current: 10 mA X-ray wavelength: Cu-Kα ray (1.5418 Å) Optical system: focusing method Slit configuration: Soller slit 4° (on both the incident and receiving sides), divergence slit 1 mm, Kβ filter (Ni plate 0.5%), air scatter screen 3 mm) Detector: semiconductor detector Measurement range: 2θ = 10-60 deg Step width, scan speed: 0.05 deg, 0.05 deg / sec From the obtained XRD pattern, a peak appearing at 2θ = 20.3° and a peak appearing at 2θ = 29.6° were identified.

[0149] (Thermogravimetric Differential Thermal Analysis (TG-DTA)) Thermogravimetric Differential Thermal Analysis (TG-DTA) was performed using a thermogravimetric differential thermal analyzer (TG-DTA) ("TGA / DSC3+ (model number)" manufactured by METTLER TOLEDO). The measurement was carried out by packing a sample (approximately 10 mg to 20 mg) in an Al pan and heating it under N ２ The temperature was raised from 30°C at a rate of 10°C / min in an atmosphere, and for the temperatures at which exothermic peaks were observed in the DTA curve, the peak top temperature of the lower exothermic peak was designated Tc1 (°C), and the peak top temperature of the higher exothermic peak was designated Tc2 (°C). The temperature difference ΔTc (=Tc2-Tc1) between the peak tops of these two exothermic peaks was calculated.

[0150] (solid ３１ P-NMR measurement) Measurement was performed using the following equipment under the following conditions: Equipment: ECZ400R (manufactured by JEOL Ltd.) Observation nuclei: ３１ P Observation frequency: 161.994 MHz Measurement temperature: room temperature Pulse sequence: single pulse 90° pulse width: 3.2 μs Waiting time after FID measurement until next pulse application: 60 s MAS (magic angle spinning) rotation speed: 11 kHz Number of accumulations: 64 Measurement range: 250 ppm to -150 ppm Sample amount: 100 mg External standard: NH ４ H ２ P.O. ４ (chemical shift 1.00 ppm)

[0151] Peak separation: When peak separation is required, the obtained solid ３１ The P-NMR spectrum is analyzed using the software "FT-NMR" (software included in "FT-NMR Data Processing by Personal Computer," Revised Edition (Second Edition) (Sankyo Publishing)) to determine the separated peaks. The software calculates the separated peaks, calculated NMR signal values, and the residual sum of squares R2 from the NMR signals (experimental values) using the nonlinear least squares method. Peak separation is considered complete when the residual sum of squares R2 within the analysis range between the experimental and calculated values, assuming the maximum peak height to be 1, is 0.007 or less and the number of separated peaks is the smallest.

[0152] Example 1 A raw material containing lithium sulfide, diphosphorus pentasulfide, diphosphorus pentoxide, lithium bromide, and lithium iodide weighed out in a molar ratio of 63.75:21.04:0.21:3.75:11.25 (total: 1.5 g) was placed in a 45 ml pot of a planetary ball mill (manufactured by Fritsch: model number P-7) together with 10 zirconia balls having a diameter of 10 mm (approximately 32 g) under a nitrogen atmosphere, completely sealed, and the pot was placed under an inert atmosphere (nitrogen atmosphere). Without heating or cooling (room temperature), the planetary ball mill was rotated at 370 rpm and mechanical milling was carried out for 40 hours. Thermogravimetric differential calorimetry was performed on the obtained powdered product (amorphous sulfide solid electrolyte), and the peak top temperature Tc1 of the exothermic peak on the lower temperature side was 208° C., the peak top temperature Tc2 of the exothermic peak on the higher temperature side was 270° C., and ΔTc was 62° C. The above product was heated at Tc1 of 208° C. for 2 hours in an inert atmosphere (nitrogen atmosphere), to obtain a crystalline sulfide solid electrolyte.

[0153] In the composition formula (1) of the obtained crystalline sulfide solid electrolyte, x, y, and z are 0.00625, 15.0000, and 0.0000, respectively, and x × y is 0.09375. The ionic conductivity of the obtained crystalline sulfide solid electrolyte was measured and found to be 4.9 mS / cm. In addition, when X-ray diffraction measurement was performed on the obtained crystalline sulfide solid electrolyte using CuKα radiation, it was found to have diffraction peaks at 2θ = 20.3 ± 0.5 ° and 29.6 ± 0.6 °, and the peak intensity at 2θ = 20.3 ° was greater than the peak intensity at 29.6 °, confirming that it had a thiolicon region II crystal structure. The X-ray diffraction pattern is shown in Figure 1.

[0154] Examples 2 to 46 Crystalline sulfide solid electrolytes of Examples 2 to 46 were prepared in the same manner as in Example 1, except that the types and blending ratios of raw materials and the pulverization conditions (manufacturing methods) in Example 1 were as shown in Tables 1 to 4. The heating temperature of the product (amorphous sulfide solid electrolyte) in these examples was the temperature Tc1 for each example. For the crystalline sulfide solid electrolyte obtained in each example, x, y, and z in the composition formula (1) are shown in Tables 1 to 4. The obtained crystalline sulfide solid electrolytes were subjected to ionic conductivity measurement, thermogravimetric differential calorimetry, and powder XRD diffraction measurement. The results are shown in Tables 1 to 4, and the X-ray diffraction patterns of Examples 2 to 10, 11 to 20, 21 to 30, 31 to 40, and 41 to 46 are shown in Figures 1 to 5, respectively.

[0155] Comparative Examples 1 to 15 Comparative sulfide solid electrolytes were prepared in the same manner as in Example 1, except that the types and blending ratios of raw materials and the pulverization conditions (production method) in Example 1 were changed to those shown in Tables 5 and 6. The resulting crystalline sulfide solid electrolytes were subjected to ionic conductivity measurement, thermogravimetric differential calorimetry, and powder XRD diffraction measurement. The results are shown in Tables 5 and 6, and the X-ray diffraction patterns of Comparative Examples 1 to 10 are shown in FIG. 6 and the X-ray diffraction patterns of Comparative Examples 11 to 15 are shown in FIG. 7.

[0156]

[0157]

[0158]

[0159]

[0160]

[0161]

[0162] The crystal structures shown in Tables 1 to 6 are as follows: R: The main crystal structure is a thiolicon region II crystal structure. L: The main crystal structure is a LGPS crystal structure. β: The main crystal structure is a β-Li ３ P.S. ４ (Crystalline Li ３ P.S. ４R+L: has both thiolicon region II type crystal structure and LGPS type crystal structure. R+β: has thiolicon region II type crystal structure and β-Li ３ P.S. ４ (Crystalline Li ３ P.S. ４ β+4141: β-Li ３ P.S. ４ (Crystalline Li ３ P.S. ４ ) and crystalline Li ４ P.S. ４ I. R + β + 4141: Thiolisine region II crystal structure, β-Li ３ P.S. ４ (Crystalline Li ３ P.S. ４ ) and crystalline Li ４ P.S. ４ I have.

[0163] The milling conditions for Production Methods 1 and 2 shown in Tables 1 to 6 are as follows. Production Method 1: The milling conditions in Example 1 were as follows: a total of 1.5 g of raw material was placed in a 45 ml zirconia pot together with 10 10 mm diameter zirconia balls (approximately 32 g) under a nitrogen atmosphere, completely sealed, and the pot was placed in an inert atmosphere (nitrogen atmosphere). Mechanical milling was performed using a planetary ball mill (manufactured by Fritsch: model number P-7) at the rotation speed and time shown in the table without heating or cooling (room temperature). Production Method 2: In Production Method 1, a total of 10 g of raw material was placed in a 500 ml zirconia pot, and a planetary ball mill (manufactured by Fritsch: model number P-5) was used as the milling device. The same procedure as Production Method 1 was used, except that the rotation speed and time shown in the table were used.

[0164] From the examples, it was confirmed that the crystalline sulfide solid electrolyte of this embodiment generally has higher ionic conductivity than the crystalline sulfide solid electrolyte of the comparative example. Furthermore, from Figures 1 to 5, it was also confirmed that the crystalline sulfide solid electrolyte of this embodiment all has diffraction peaks at 2θ = 20.3 ° and 29.6 °, and it was confirmed that it has at least one crystal structure of a thiolicon region II type crystal structure and an LGPS type crystal structure.

[0165] Regarding the comparative examples, the crystalline sulfide solid electrolytes of Comparative Examples 2 to 4 and 11 to 13 had a thiolicon region II type crystal structure, but because they did not contain halogen atoms, their ionic conductivities were all low and did not reach the ionic conductivities of the crystalline sulfide solid electrolytes of the Examples. The low ionic conductivities of the crystalline sulfide solid electrolytes of Comparative Examples 11 to 13 are thought to be due in part to the fact that the diffraction peaks of the raw material lithium sulfide were confirmed. The crystalline sulfide solid electrolyte of Comparative Example 1 did not contain halogen atoms and did not contain crystalline Li ３ P.S. ４ Since the crystalline sulfide solid electrolytes of Comparative Examples 5 to 10 contained halogen atoms but no oxygen atoms, the crystalline sulfide solid electrolytes of Comparative Examples 5, 6, and 8 to 10 also did not reach the ionic conductivity of the crystalline sulfide solid electrolytes of the Examples. Although the ionic conductivity of the crystalline sulfide solid electrolyte of Comparative Example 7 was similar to that of the crystalline sulfide solid electrolyte of some Examples (Example 30), the amount of raw materials containing halogen atoms was large, and it could not be said to be a sulfide solid electrolyte with reduced raw material costs.

[0166] The crystalline sulfide solid electrolyte of Comparative Example 14 has a composition formula (1) in which z is −0.1818 and Li ３ P.S. ４Although it has a composition in which the ratio of lithium atoms to sulfur atoms from the structure is significantly different, due to the large deviation in the basic skeleton, it does not have either a thiolisiconregion II crystal structure or an LGPS crystal structure, and the ionic conductivity was low. Furthermore, the crystalline sulfide solid electrolyte of Comparative Example 15 was not sufficiently pulverized during production, so it did not have a specific diffraction peak. Therefore, the ionic conductivity was extremely low. From the above results, it was confirmed that the crystalline sulfide solid electrolyte of this embodiment contains lithium atoms, sulfur atoms, phosphorus atoms, oxygen atoms, and halogen atoms, and has a specific diffraction peak and composition in X-ray diffraction measurement, thereby achieving high ionic conductivity.

[0167] For the crystalline sulfide solid electrolytes of Examples 9, 11, 17, 19 and 23, ３１ The solid state of the crystalline sulfide solid electrolyte obtained in these examples was measured by P-NMR. ３１ The P-NMR spectra are shown in Figures 8 and 9. ３１ Using the data obtained by P-NMR measurement, the phosphorus ratio (mol%) contained in each structure was calculated based on the peak area attributable to each structure. Specifically, the phosphorus ratio (mol%) contained in each structure was calculated from the ratio of the peak area of ​​each structure to the total area of ​​the peaks attributable to each structure shown in Table 7. The calculated phosphorus ratio (mol%) of each structure is shown in Table 7.

[0168]

[0169] In Table 7, "R" indicates the thiolicon region II crystal structure.

[0170] As shown in Table 7, the crystalline sulfide solid electrolytes of Examples 9, 11, 17, 19 and 23 all exhibited PSO ３ ３－ A peak due to PO was observed. ４ ３－ and P.S. ２ O ２ ３－Peaks due to the incorporation of oxygen atoms into the crystal structure were also observed, indicating that oxygen atoms were incorporated into the crystal structure. Furthermore, it was confirmed that the crystalline sulfide solid electrolytes of these examples had a thiolisiconregion II crystal structure and high ionic conductivities of 3.7, 4.7, 2.5, 2.3, and 2.9 mS / cm, respectively, despite the use of a small amount of raw material containing halogen atoms, at 10.0 to 15.0 mol%. From this, it was found that by incorporating oxygen atoms into the crystal structure, a sulfide solid electrolyte having a thiolisiconregion II crystal structure that exhibits high ionic conductivity even with a low halogen atom content can be obtained, and that a sulfide solid electrolyte having a thiolisiconregion II crystal structure that exhibits higher ionic conductivity can be obtained when the halogen atom content is relatively high.

[0171] The crystalline sulfide solid electrolyte of this embodiment has high ionic conductivity, further realizes reduction in raw material costs, and has excellent battery performance, so it is suitable for use, for example, in combination with an electrode active material to form an electrode composite, or in lithium ion batteries. Lithium ion batteries are suitable for use in information-related devices and communication devices such as personal computers, video cameras, and mobile phones.

Claims

1. A solid that contains lithium atoms, phosphorus atoms, sulfur atoms, oxygen atoms, and halogen atoms, and has diffraction peaks at 2θ = 20.3 ± 0.5 ° and 29.6 ± 0.6 ° in X-ray diffraction measurement using CuKα rays. ３１ P-NMR measurement showed PSO at 39.6±5.0 ppm. ３ ３－ A crystalline sulfide solid electrolyte in which a peak due to (Li) is observed and which has a composition represented by the following composition formula (1). ３＋２ｚ P (S １－ｘ O ｘ ) ４＋ｚ )+(y)LiX (1) (In the composition formula (1), x, y, and z each satisfy 0.00060≦x≦0.15, 3.0≦y<25.0, and −0.17≦z≦1.

5. X represents a halogen atom.) 2. The crystalline sulfide solid electrolyte according to claim 1, wherein in the composition formula (1), the product of x and y (x × y) is 0.0010 or more and 2.7 or less.

3. Solid ３１ P-NMR measurement revealed that PO was present at 9.2±5.0 ppm. ４ ３－ The crystalline sulfide solid electrolyte according to claim 1 or 2, in which a peak due to is observed.

4. Solid ３１ P-NMR measurement revealed that PS was present at 70.3±5.0 ppm. ２ O ２ ３－ The crystalline sulfide solid electrolyte according to any one of claims 1 to 3, in which a peak due to is observed.

5. A crystalline sulfide solid electrolyte according to any one of claims 1 to 4, in which at least two exothermic peaks are measured in a thermogravimetric differential calorimetry (measured at a heating rate of 10°C / min), and the temperature difference between the peak tops of the two exothermic peaks is 20°C or more and 110°C or less.

6. The crystalline sulfide solid electrolyte according to any one of claims 1 to 5, wherein the halogen atom is at least one kind of halogen atom selected from the group consisting of chlorine atoms, bromine atoms, and iodine atoms.

7. The crystalline sulfide solid electrolyte according to any one of claims 1 to 6, wherein the halogen atoms are bromine atoms and iodine atoms.

8. The crystalline sulfide solid electrolyte according to any one of claims 1 to 7, wherein in the composition formula (1), y satisfies 14.0<y<25.

0.

9. The crystalline sulfide solid electrolyte according to any one of claims 1 to 8, having an ionic conductivity of 0.85 mS / cm or more.

10. The crystalline sulfide solid electrolyte according to any one of claims 1 to 9, having an ionic conductivity of 2.5 mS / cm or more.

11. A crystalline sulfide solid electrolyte according to any one of claims 1 to 10, which does not contain at least one metal atom selected from the group consisting of sodium atoms, boron atoms, aluminum atoms, silicon atoms, germanium atoms, arsenic atoms, selenium atoms, antimony atoms, tellurium atoms, lead atoms, and bismuth atoms.

12. The oxygen atom is P ２ O ５ The crystalline sulfide solid electrolyte according to any one of claims 1 to 11, which is derived from 13. The crystalline sulfide solid electrolyte according to any one of claims 1 to 12, which is a glass ceramic.

14. A solid that contains lithium atoms, phosphorus atoms, sulfur atoms, oxygen atoms, and halogen atoms, and has diffraction peaks at 2θ = 20.3 ± 0.5 ° and 29.6 ± 0.6 ° in X-ray diffraction measurement using CuKα rays. ３１ P-NMR measurement showed PSO at 39.6±5.0 ppm. ３ ３－ A peak due to the crystalline sulfide solid electrolyte is observed.

15. Solid ３１ P-NMR measurement revealed that PO was present at 9.2±5.0 ppm. ４ ３－ The crystalline sulfide solid electrolyte according to claim 14, in which a peak due to is observed.

16. Solid ３１ P-NMR measurement revealed that PS was present at 70.3±5.0 ppm. ２ O ２ ３－The crystalline sulfide solid electrolyte according to claim 14 or 15, in which a peak due to is observed.

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